The VTOC and catalog is updated. SMS writes an EOF record on the first track, non-SMS gets the last contents.
On Fri, May 13, 2022 at 3:52 AM CM Poncelet <000003e99a92061c-dmarc-requ...@listserv.ua.edu> wrote: > > I could be wrong, but I had the vague impression that allocating > datasets via IEFBR14 did not *physically* allocate them on DASD - but > that they were physically allocated only when an 'OPEN for WRITE' was > issued against them. BTW I cannot check this, as I have no access to a > mainframe (8+ years.) > > > > On 12/05/2022 15:06, Pommier, Rex wrote: > > David, > > > > My point was that if you allocate the dataset with a very small primary and > > large secondary, if the dataset is never opened, you've only wasted a > > cylinder of space instead of 500. I just played with Richard's suggestion > > of using SPACE(CYL(0,500),RLSE) and it works just fine, allocating no space > > unless the dataset actually gets opened and data written to it. For some > > reason I had it stuck in my head that strange things happened if you set a > > primary space of 0 but that doesn't appear to be the case. So even in my > > old age I learned something. :-) > > > > Rex > > > > -----Original Message----- > > From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of > > <David> <Mingee> > > Sent: Wednesday, May 11, 2022 4:30 PM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: Re: [EXTERNAL] Re: Potential Resource Savings Techniques > > > > Great technique. What utility or JCL is being used, if the dataset is not > > opened then RLSE does not happen. > > > > -----Original Message----- > > From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of > > Pommier, Rex > > Sent: Wednesday, May 11, 2022 5:20 PM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: Re: [EXTERNAL] Re: Potential Resource Savings Techniques > > > > David, > > > > Here's another solution to that scenario. We have several datasets that > > historically got allocated like you show here on a nightly basis. The jobs > > would either populate the datasets or not even open them. I had the > > developer change the JCL to allocate them with SPACE(CYL(1,500),RLSE). > > Dataset doesn't get populated? No problem, 1 cylinder used. If it gets > > populated, it typically fills up 1 or 2 extents. No more huge amounts of > > wasted space. > > > > Rex > > > > -----Original Message----- > > From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of > > <David> <Mingee> > > Sent: Wednesday, May 11, 2022 4:13 PM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: [EXTERNAL] Re: Potential Resource Savings Techniques > > > > My 2nd apology. The main reason for using this IDCAMS method is to reduce > > wasted disk space for empty files. Sometimes empty files are Updated with > > data after they are created and sometimes they just remain empty. One user > > created a few hundred of these each month with > > SPACE=(CYL,(500,200),RLSE) . So IDCAMS creating them saved 1000's of CYLs > > of DISK. > > > > -----Original Message----- > > From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of > > Paul Gilmartin > > Sent: Wednesday, May 11, 2022 4:21 PM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: Re: Potential Resource Savings Techniques > > > > On Wed, 11 May 2022 15:36:01 -0400, wrote: > > > >> I apologize to all. The Correct JCL is below. It must use INFILE of DD > >> DUMMY. > >> > > How do IEFBR14, IEBGENER, and IDCAMS compare in behavior and performance? > > I'd expect: > > IEFBR14 fails to RLSE. > > IEBGENER is simplest to code for a single data set. > > IDCAMS has best performance for multiple data sets because it minimizes job > > step overhead. > > > > Is there any purpose in allocating a primary with multiple storage units > > then immediately RLSE, other than demonstration? > > > > I recall I was told that the EOF is written automatically if the SMS > > address space is active, regardless whether the data set is SMS managed. > > > > How does this play with data recovery by allocating with ABSTRK? > > > > I prefer BLKSIZE=0. SDB knows best. > > > >> IDCAMS TO ALLOCATE EMPTY FILE VS USING IEFBR14 AS BR14 DOES NOT USE SDB > >> or RLSE SPACE > >> //STEP010 EXEC PGM=IDCAMS > >> //DD1 DD DUMMY CAN USE DD DUMMY OR DD * WITH NO DATA > >> //DD2 DD DSN=GRT.GIOIDXM.TEST.BLK1(+1), > >> // DISP=(NEW,CATLG,DELETE), > >> // DCB=(BLKSIZE=0,DSORG=PS,LRECL=80,RECFM=FB), > >> // SPACE=(CYL,(100,200),RLSE),UNIT=DISK > >> //DD3 DD DSN=GRT.GIOIDXM.TEST.BLK2, > >> // DISP=(NEW,CATLG,DELETE), > >> // DCB=(BLKSIZE=0,DSORG=PS,LRECL=80,RECFM=FB), > >> // SPACE=(TRK,(180,180),RLSE),UNIT=DISK > >> //SYSPRINT DD SYSOUT=* > >> //SYSIN DD * > >> REPRO INFILE(DD1) OUTFILE(DD2) > >> REPRO INFILE(DD1) OUTFILE(DD3) > >> /* > > -- > > gil > > > > ---------------------------------------------------------------------- > > 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 > > > > ---------------------------------------------------------------------- > > The information contained in this message is confidential, protected from > > disclosure and may be legally privileged. If the reader of this message is > > not the intended recipient or an employee or agent responsible for > > delivering this message to the intended recipient, you are hereby notified > > that any disclosure, distribution, copying, or any action taken or action > > omitted in reliance on it, is strictly prohibited and may be unlawful. If > > you have received this communication in error, please notify us immediately > > by replying to this message and destroy the material in its entirety, > > whether in electronic or hard copy format. Thank you. > > > > > > ---------------------------------------------------------------------- > > 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 > > > > ---------------------------------------------------------------------- > > The information contained in this message is confidential, protected from > > disclosure and may be legally privileged. If the reader of this message is > > not the intended recipient or an employee or agent responsible for > > delivering this message to the intended recipient, you are hereby notified > > that any disclosure, distribution, copying, or any action taken or action > > omitted in reliance on it, is strictly prohibited and may be unlawful. If > > you have received this communication in error, please notify us immediately > > by replying to this message and destroy the material in its entirety, > > whether in electronic or hard copy format. Thank you. > > > > > > ---------------------------------------------------------------------- > > 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 -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
