Re: Searching the ASVT
On 2/5/2023 9:14 AM, Joe Monk wrote: I always find it fascinating when someone tries to explain to the IBM z/OS designers how z/OS works... Not sure I follow what you're trying to say with this snarky-sounding comment, particularly since Michael Stein's explanation was correct... -- Phoenix Software International Edward E. Jaffe 831 Parkview Drive North El Segundo, CA 90245 https://www.phoenixsoftware.com/ This e-mail message, including any attachments, appended messages and the information contained therein, is for the sole use of the intended recipient(s). If you are not an intended recipient or have otherwise received this email message in error, any use, dissemination, distribution, review, storage or copying of this e-mail message and the information contained therein is strictly prohibited. If you are not an intended recipient, please contact the sender by reply e-mail and destroy all copies of this email message and do not otherwise utilize or retain this email message or any or all of the information contained therein. Although this email message and any attachments or appended messages are believed to be free of any virus or other defect that might affect any computer system into which it is received and opened, it is the responsibility of the recipient to ensure that it is virus free and no responsibility is accepted by the sender for any loss or damage arising in any way from its opening or use. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
> ASVTENTY is the address of the entry for ASID 0 (which, of course, is never > used). Apologies. That's wrong. ASVTENTY is, as others have posted, the entry for ASID 1. ASVTFRST locates an entry that is available for use for a new address space. Peter Relson z/OS Core Technology Design -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
I always find it fascinating when someone tries to explain to the IBM z/OS designers how z/OS works... Joe On Sun, Feb 5, 2023 at 9:16 AM Michael Stein wrote: > On Sun, Feb 05, 2023 at 01:34:36PM +, Peter Relson wrote: > > > ASVTFRST is documented as "address of first available ASVT entry". It > > has nothing to do with "next". > > ASVTFRST is the address of the slot for ASID 0 which doesn't exist but > is usefull to adjust for the fact that ASIDs start at 1 since it is > just before ASVTENTY. > > > The ASVT entries form an array with the first being at ASVTENTY, > > and each entry mapped by 4-byte field ASVTENTY.] > > ASVTENTY is the slot for ASID 1 and the actual start of the slots > which (might) point to ASCBs. > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
On Sun, Feb 05, 2023 at 07:12:57AM +, Seymour J Metz wrote: > Shouldn't that be > USING ASVTBEGN,R10 ESTABLISH ADDRESSABILITY > > Or does CVTASVT point to the prefix? It points to the prefix. This allows IBM to add fields to the ASVT without the other offsets changing. They can't add them at the end since the end has an unknown number of slots for ASCB addresses. It's possible (likely?) that the full prefix doesn't exist as allocated storage to the ASVT (ie: the unused part of the prefix overlays something else). There is a lot of code which knows the ASVT structure and possibly micro-code too... -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
It looks correct, but I have a few style comments. Use of "magic numbers" can obscure the code; I'd use the symbol from IHAPSA The extraneous DROP R10 before USING ASVT,R10 is confusing. You don't need to bump the pointer to AVTENTY before the loop. Something like USING PSA,R0 L R10,CVTPTR USING CVTMAP,R10 L R11,CVTASVT USING ASVT,R11 L R9,ASVTMAXU LOOPASVT TMASVTENTY,ASVTAVAL BONEXTASVT L R10,ASVTENTY USING ASCB,R10 ... NEXTASVT LAR11,4(,R11) BCT R9,LOOPASVT ... IHAPSA , CVT DSECT=YES IHAASVT , ... Also, please read Peter's message. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Bernd Oppolzer [bernd.oppol...@t-online.de] Sent: Sunday, February 5, 2023 5:33 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Searching the ASVT Thank you all for this discussion; I have learned something new :-) Would you kindly look at this coding and tell me, if it is correct in your opinion, and if it is allowed to execute this by non-privileged programs? What macro calls do I need to get the needed definitions (CVT, ASVT, ASCB)? Thanks in advance, have a nice day Bernd * *- *walk thru all ASCBs *- * L R10,16 LOAD ADDR OF CVT USING CVT,R10 SET ADDRESSABILITY TO CVT L R10,CVTASVT POINT TO ADDRESS SPACE VECTOR TABLE DROP R10 USING ASVT,R10SET ADDRESSABILITY TO ASVT L R9,ASVTMAXU LOAD MAX. NUMBER OF ADDRESS SPACES. LAR11,ASVTENTYLOAD ADDRESS OF FIRST ASCB POINTER DROP R10 * *- *R11 is moved over the table of all ASCB pointers *R10 is no longer needed *R9 contains the number of entries in the ASCB table *- * LOOPASVT DS0H TM0(R11),ASVTAVAL VALID ASCB Available ? BONEXTASVTNO, CHECK NEXT ASVT ENTRY * *- *Examine ASCB *Use R10 to address the ASCB *- * L R10,0(R11) USING ASCB,R10 * *- *access fields of current ASCB *- * *--- to be entered here --- * *- *advance R11 to next ASCB address *- * NEXTASVT DS0H LAR11,4(,R11) Advance to NEXT ASVT ENTRY BCT R9,LOOPASVT * Am 05.02.2023 um 07:39 schrieb Tony Harminc: > On Sat, 4 Feb 2023 at 18:00, esst...@juno.com wrote: > > >> I am on a z/os 2.2 system, trying to rseurrect some old code. >> . >> can some one confirm the instructions for Searching the >> Address Space Vector Table (ASVT) on z/OS 2.2 >> . >> This program loads R10 with CVTASVT >> L R10,CVTASVTGET ASVT ADDRESS >> USING ASVT,R10 ESTABLISH ADDRESSABILITY >> > That's fine. > > >> It then issues a Load Address For the first entry ? >> This doesn't look correct to me ? >> LAR11,ASVTENTY GET # OF FIRST ENTRY >> > It's fine. The ASVT has a bunch of header stuff, and then an array of > fullword pointers starting at ASVTENTY. The PL/X declaration may make it a > bit clearer. > > Next its test for an ASCB that is assigned. >> TM0(R11),ASVTAVALVALID ASCB Available ? >> BORUNLOP1NO, CHECK NEXT ASVT ENTRY >> > It's fine.I suppose there may be a serialization issue, e.g. an ASVT > entry's assignment status may change after you've looked. But programs that > either index the ASVT with the ASID (x 4), or those that go sequentially > through the array and do with each active address space have > done it this way forever (i.e. since 1972), and I'm sure many are still out > there working fine. Like anything, it's conceivable IBM could change this > at some point, but it's such a basic interface in MVS--> z/OS that they > would surely introduce some new data structure or API to access the list of > ASCBs rather than change the ASVT and break things all over the place. > > >> Besides
Re: Searching the ASVT
On Sun, Feb 05, 2023 at 01:34:36PM +, Peter Relson wrote: > ASVTFRST is documented as "address of first available ASVT entry". It > has nothing to do with "next". ASVTFRST is the address of the slot for ASID 0 which doesn't exist but is usefull to adjust for the fact that ASIDs start at 1 since it is just before ASVTENTY. > The ASVT entries form an array with the first being at ASVTENTY, > and each entry mapped by 4-byte field ASVTENTY.] ASVTENTY is the slot for ASID 1 and the actual start of the slots which (might) point to ASCBs. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
> Next its test for an ASCB that is assigned. > > TM0(R11),ASVTAVALVALID ASCB Available ? > > BORUNLOP1NO, CHECK NEXT ASVT ENTRY I wouldn't separate the test for valid with picking up the ASCB address as the ASVT slot might change between my ASVT references. I'd load the word from the ASVT slot and then test the high bit in the register (LTR or ICM). I'm assuming you don't hold the required locks to serialize ASVT updates (unlike deep in the zOS dispatcher etc..) -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
Before addressing the question, a question in return. Why are you searching the ASVT? Most user ASVT references relate to finding the ASCB address for a specific ASID. LOCASCB is usually used for that. If you must search the ASVT, do you have reason to doubt the current code? What are you searching for? Do you have the serialization you need to safeguard whatever it is that you are doing? How are you determining how far to go? You might find using ASVTHWMAsid to meet your needs rather than ASVTMAXU, if you happen to know you are running on z/OS 2.4 or later. The comment on the "LA" is obviously incorrect, assuming "#" is "number". ASVTENTY is the address of the entry for ASID 0 (which, of course, is never used). ASVTFRST is documented as "address of first available ASVT entry". It has nothing to do with "next". The ASVT entries form an array with the first being at ASVTENTY, and each entry mapped by 4-byte field ASVTENTY. Peter Relson z/OS Core Technology Design -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
Personally, I would take a dump and use IPCS to go through the pointers with pencil and paper to make sure I understand the linkage, and it points to what I want. For example, to find the job name from an ASCB is either pASCB+ASCBJBNI or pASCB+ASCBJBNS depending if it is a job or started task. You can use the runchain IPCS command to run a chain... then do it in your code. Colin On Sat, 4 Feb 2023 at 23:00, esst...@juno.com wrote: > . > Hello > > I am on a z/os 2.2 system, trying to rseurrect some old code. > . > can some one confirm the instructions for Searching the > Address Space Vector Table (ASVT) on z/OS 2.2 > . > This program loads R10 with CVTASVT > L R10,CVTASVTGET ASVT ADDRESS > USING ASVT,R10 ESTABLISH ADDRESSABILITY > . > It then issues a Load Address For the first entry ? > This doesn't look correct to me ? > LAR11,ASVTENTY GET # OF FIRST ENTRY > . > Next its test for an ASCB that is assigned. > TM0(R11),ASVTAVALVALID ASCB Available ? > BORUNLOP1NO, CHECK NEXT ASVT ENTRY > . > * Examine ASCB > . > . > Besides the Load Address above - How should this module > advance to the Next ASVT entry ? > Shoud I issue the following to get to the next ASVT > LR10,ASVTFRST > . > The current code issues the following instruction, which > looks incorrect according to IHAASVT > LAR11,4(,R11) Advance NEXT ASVT ENTRY > . > . > Your comments please > . > Paul D'Angelo > *** > > -- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
Thank you all for this discussion; I have learned something new :-) Would you kindly look at this coding and tell me, if it is correct in your opinion, and if it is allowed to execute this by non-privileged programs? What macro calls do I need to get the needed definitions (CVT, ASVT, ASCB)? Thanks in advance, have a nice day Bernd * *- * walk thru all ASCBs *- * L R10,16 LOAD ADDR OF CVT USING CVT,R10 SET ADDRESSABILITY TO CVT L R10,CVTASVT POINT TO ADDRESS SPACE VECTOR TABLE DROP R10 USING ASVT,R10 SET ADDRESSABILITY TO ASVT L R9,ASVTMAXU LOAD MAX. NUMBER OF ADDRESS SPACES. LA R11,ASVTENTY LOAD ADDRESS OF FIRST ASCB POINTER DROP R10 * *- * R11 is moved over the table of all ASCB pointers * R10 is no longer needed * R9 contains the number of entries in the ASCB table *- * LOOPASVT DS 0H TM 0(R11),ASVTAVAL VALID ASCB Available ? BO NEXTASVT NO, CHECK NEXT ASVT ENTRY * *- * Examine ASCB * Use R10 to address the ASCB *- * L R10,0(R11) USING ASCB,R10 * *- * access fields of current ASCB *- * * --- to be entered here --- * *- * advance R11 to next ASCB address *- * NEXTASVT DS 0H LA R11,4(,R11) Advance to NEXT ASVT ENTRY BCT R9,LOOPASVT * Am 05.02.2023 um 07:39 schrieb Tony Harminc: On Sat, 4 Feb 2023 at 18:00, esst...@juno.com wrote: I am on a z/os 2.2 system, trying to rseurrect some old code. . can some one confirm the instructions for Searching the Address Space Vector Table (ASVT) on z/OS 2.2 . This program loads R10 with CVTASVT L R10,CVTASVTGET ASVT ADDRESS USING ASVT,R10 ESTABLISH ADDRESSABILITY That's fine. It then issues a Load Address For the first entry ? This doesn't look correct to me ? LAR11,ASVTENTY GET # OF FIRST ENTRY It's fine. The ASVT has a bunch of header stuff, and then an array of fullword pointers starting at ASVTENTY. The PL/X declaration may make it a bit clearer. Next its test for an ASCB that is assigned. TM0(R11),ASVTAVALVALID ASCB Available ? BORUNLOP1NO, CHECK NEXT ASVT ENTRY It's fine.I suppose there may be a serialization issue, e.g. an ASVT entry's assignment status may change after you've looked. But programs that either index the ASVT with the ASID (x 4), or those that go sequentially through the array and do with each active address space have done it this way forever (i.e. since 1972), and I'm sure many are still out there working fine. Like anything, it's conceivable IBM could change this at some point, but it's such a basic interface in MVS--> z/OS that they would surely introduce some new data structure or API to access the list of ASCBs rather than change the ASVT and break things all over the place. Besides the Load Address above - How should this module advance to the Next ASVT entry ? There's nothing wrong with the LA. The start of the array of ASCB pointers is at whatever offset ASVTENTY is at, and that hasn't changed in 50 years. The content of the header info has grown, but not the offset of the array of pointers. Shoud I issue the following to get to the next ASVT LR10,ASVTFRST No. I think you're thinking that the entire ASVT has multiple instances that are chained together. There's only one, with an array of pointers on the end. ASVTFRST points somewhere you don't want - I think the first *available* ASCB, though IBM doesn't document the ASCB creation logic, and I assume things have changed with reusable ASIDs. Presumably you are not planning to modify the ASVT, so you're not looking for an available entry... If you are, well Just Don't. But effectively ASVTFRST is element 0 of the array of ASCB pointers, and there's no ASID 0. So if you have the address of ASVTFRST (not the address that is *in* ASVTFRST), then you can multiply the ASID by 4 and use it as an origin-0 array index. If you start at ASVTENTY then it's origin-1, so add 4 (or 1 before you multiply by 4). Or if you want to look at all active ASCBs then start with the first array element, follow the pointer *if it's active*, and
Re: Searching the ASVT
Shouldn't that be USING ASVTBEGN,R10 ESTABLISH ADDRESSABILITY Or does CVTASVT point to the prefix? The LAR11,ASVTENTY is unnecessary unless you need to refer to the base of the table again; if you include it then include a corresponding USING. Otherwise you can just use and increment R10. LAR11,4(,R11) is correct for the code shown. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of esst...@juno.com [esst...@juno.com] Sent: Saturday, February 4, 2023 5:58 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Searching the ASVT . Hello I am on a z/os 2.2 system, trying to rseurrect some old code. . can some one confirm the instructions for Searching the Address Space Vector Table (ASVT) on z/OS 2.2 . This program loads R10 with CVTASVT L R10,CVTASVTGET ASVT ADDRESS USING ASVT,R10 ESTABLISH ADDRESSABILITY . It then issues a Load Address For the first entry ? This doesn't look correct to me ? LAR11,ASVTENTY GET # OF FIRST ENTRY . Next its test for an ASCB that is assigned. TM0(R11),ASVTAVALVALID ASCB Available ? BORUNLOP1NO, CHECK NEXT ASVT ENTRY . * Examine ASCB . . Besides the Load Address above - How should this module advance to the Next ASVT entry ? Shoud I issue the following to get to the next ASVT LR10,ASVTFRST . The current code issues the following instruction, which looks incorrect according to IHAASVT LAR11,4(,R11) Advance NEXT ASVT ENTRY . . Your comments please . Paul D'Angelo *** -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
On Sat, 4 Feb 2023 at 18:00, esst...@juno.com wrote: > I am on a z/os 2.2 system, trying to rseurrect some old code. > . > can some one confirm the instructions for Searching the > Address Space Vector Table (ASVT) on z/OS 2.2 > . > This program loads R10 with CVTASVT > L R10,CVTASVTGET ASVT ADDRESS > USING ASVT,R10 ESTABLISH ADDRESSABILITY > That's fine. > It then issues a Load Address For the first entry ? > This doesn't look correct to me ? > LAR11,ASVTENTY GET # OF FIRST ENTRY > It's fine. The ASVT has a bunch of header stuff, and then an array of fullword pointers starting at ASVTENTY. The PL/X declaration may make it a bit clearer. Next its test for an ASCB that is assigned. > TM0(R11),ASVTAVALVALID ASCB Available ? > BORUNLOP1NO, CHECK NEXT ASVT ENTRY > It's fine.I suppose there may be a serialization issue, e.g. an ASVT entry's assignment status may change after you've looked. But programs that either index the ASVT with the ASID (x 4), or those that go sequentially through the array and do with each active address space have done it this way forever (i.e. since 1972), and I'm sure many are still out there working fine. Like anything, it's conceivable IBM could change this at some point, but it's such a basic interface in MVS--> z/OS that they would surely introduce some new data structure or API to access the list of ASCBs rather than change the ASVT and break things all over the place. > Besides the Load Address above - How should this module > advance to the Next ASVT entry ? > There's nothing wrong with the LA. The start of the array of ASCB pointers is at whatever offset ASVTENTY is at, and that hasn't changed in 50 years. The content of the header info has grown, but not the offset of the array of pointers. > Shoud I issue the following to get to the next ASVT > LR10,ASVTFRST > No. I think you're thinking that the entire ASVT has multiple instances that are chained together. There's only one, with an array of pointers on the end. ASVTFRST points somewhere you don't want - I think the first *available* ASCB, though IBM doesn't document the ASCB creation logic, and I assume things have changed with reusable ASIDs. Presumably you are not planning to modify the ASVT, so you're not looking for an available entry... If you are, well Just Don't. But effectively ASVTFRST is element 0 of the array of ASCB pointers, and there's no ASID 0. So if you have the address of ASVTFRST (not the address that is *in* ASVTFRST), then you can multiply the ASID by 4 and use it as an origin-0 array index. If you start at ASVTENTY then it's origin-1, so add 4 (or 1 before you multiply by 4). Or if you want to look at all active ASCBs then start with the first array element, follow the pointer *if it's active*, and do whatever it is you want to do with each ASCB. > The current code issues the following instruction, which > looks incorrect according to IHAASVT > LAR11,4(,R11) Advance NEXT ASVT ENTRY > It's fine. I suppose if you want to be pedantic you could use L'ASVTENTY instead of hardcoding 4, but seriously, that's not going to change, and if it does all kinds of other things will break. Tony H. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
Hi, I'm not sure what you are trying to do, Most people would use the ASVT to get tot he ACSB to see what's running. If it is that you are trying to search the ASCB to see if a task is actually executing, then all you really need from the ASVT is max number of ASCBS (located in ASVTMAXU) and the pointer to the first ACSB entry (located in ASVTENTY). You load ASVTMAXU into a register (let's say R14) and LA ASVTENTY into a Reg (let's say R6) L R6,16 LOAD ADDR OF CVT USING CVT,R6 SET ADDRESSABILITY TO CVT L R6,CVTASVT POINT TO ADDRESS SPACE VECTOR TABLE. DROP R6 DROP ADDRESSABILITY TO CVT USING ASVT,R6 SET ADDRESSABILITY TO ASVT L R14,ASVTMAXU LOAD MAX. NUMBER OF ADDRESS SPACES. LAR6,ASVTENTYLOAD ADDRESS OF FIRST ASCB POINTER DROP R6 DROP ADDRESSABILITY TO ASVT then you loop until you find what you want JOBSRCH2 ICM R3,B'',0(R6)POINT TO ASCB BNP JOBSRCH5ZERO OR NEGATIVE, BYPASS THIS ONE USING ASCB,R3 SET ADDRESSABILITY TO ASCB ICM R15,B'',ASCBJBNI LOAD ADDRESS OF JOB NAME BZJOBSRCH3ZERO, NOT A BATCH JOB must be STC MVC SRCHNAME,0(R15) SAVE JOB NAME B JOBSRCH4GO SEE IF REQUESTED JOB/TASK NAME JOBSRCH3 EQU * Not a batch job, must be STC ICM R15,B'',ASCBJBNS LOAD ADDRESS OF STC TASK NAME MVC SRCHNAME,0(R15) SAVE TASK NAME ... then you compare SRCHNAME to whatever you are looking for or just move it to print if you are just listing them ..then you just keep looping until you hit the end of the ASCBs JOBSRCH5 LAR6,4(R6)POINT TO NEXT ASCB POINTER. BCT R14,JOBSRCH2LOOP THROUGH ASCBS If you object is to just scan the ASVT, then I have to ask why you would need to do that? Brian -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Searching the ASVT
> I am on a z/os 2.2 system, trying to rseurrect some old code. > . > can some one confirm the instructions for Searching the > Address Space Vector Table (ASVT) on z/OS 2.2 > . > This program loads R10 with CVTASVT > L R10,CVTASVTGET ASVT ADDRESS > USING ASVT,R10 ESTABLISH ADDRESSABILITY > . > It then issues a Load Address For the first entry ? > This doesn't look correct to me ? > LAR11,ASVTENTY GET # OF FIRST ENTRY > . > Next its test for an ASCB that is assigned. > TM0(R11),ASVTAVALVALID ASCB Available ? > BORUNLOP1NO, CHECK NEXT ASVT ENTRY > . > * Examine ASCB > . > The current code issues the following instruction, which > looks incorrect according to IHAASVT > LAR11,4(,R11) Advance NEXT ASVT ENTRY ASVT mapping: https://www.ibm.com/docs/en/zos/2.2.0?topic=information-asvt-mapping That looks correct to me. Here's some code from MVS3.8 IEAVEAC0: L R1,CVTASVT-CVT(R1) GET THE ASVT 63660002 BCTR R13,ZERO ASID-163710002 SLL R13,TWO(ASID-1) X 4 63730002 L R13,ASVTENTY-ASVT(R13,R1) GET ASCB ADDRESS @YM01596 63750002 So each slot in the ASVT is a 4 byte pointer with the high bit off if points to an ASCB. ASID 0 doesn't exist, so ASVTENTY is the pointer for ASID 1. It does need some check to not run off the end of the ASVT... https://www.ibm.com/docs/en/zos/2.2.0?topic=information-asvt-heading Size: Offset of ASVTEND minus offset of ASVTBEGN plus four times the value of ASVTMAXU. I'd guess that there are ASVTMAXU 4 byte entries starting and counting ASVTENTY. -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
