Billy, If it is an internal sort then supply the FILSZ=Ennnnnnnnnnn parameter in DFSPARM (or $ORTPARM for Syncsort) along with the DYNALLOC parameter.
My shop defaults DYNALLOC to 59 and allows production jobs to use the max of 255 for particularly large sorts. Some of ours are, like yours, multiple hundreds of millions of relatively short records, and DYNALLOC is used all the time for those, no JCL SORTWK at all. My team has a standing policy to: (1) remove SORTWKnn from JCL and PROC's that have them when they are next updated (2) add the appropriate xxxxPARM JCL if not already there (3) add/update PARM control card(s): DYNALLOC larger than default if needed by testing on production volume files; for internal SORT's also add FILSZ=Ennn at about 1.2 times current volume unless there is known future growth anticipated (4) enlarge too-small REGION parameters to at least 512M for large sort steps (internal or external) and higher if needed up to the installation-controlled max Let SORT do the work for you, there is really no need to do that work yourself. HTH Peter -----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Billy Ashton Sent: Monday, July 3, 2023 3:48 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: SORTWK space usage Doug, this raises a good point. If I have a COBOL program doing a SORT in the middle of the program (I am not sure if the big file is doing this, too or not), is using this DFSPARM the best way to force the use of 15 Dynalloc SORTWK files, so I would not have to code SORTWK DD statements? Thank you and best regards, Billy Ashton ------ Original Message ------ From "Doug" <dsh...@bellsouth.net> To IBM-MAIN@listserv.ua.edu Date 7/3/2023 2:45:28 PM Subject Re: SORTWK space usage >Try adding this instead off sorted dd. >//DFSPARM DD * > OPTION DYNALLOC=(SYSDA,15),DYNSPC=768 >/* > >You can add other options too. >Regards, Doug > >On Jul 3, 2023, at 14:34, Michael Oujesky <reflect...@oujesky.net> wrote: > >Just a warning, but the SORTWK specification decision depends on how SORT is >provided the input data. If via SORTIN, then allowing SORT to make the >determination should be fine. But when the incoming records are provided SORT >one records at a time (piping, E15 exit, etc,) then nudging SORT's SORTWK >decision by providing some SORTWK areas would probably be a better approach. > >At 01:13 PM 7/3/2023, Billy Ashton wrote: > >> Thanks everyone - these are good recommendations. >> >> However, the guy who came to me first has a job that sorts 450 million >> records of 110 bytes, and I can't see how I could run SORT without >> specifying SORTWK DD statements. Are there special configuration options I >> can verify that we have in place to help my comfort level that I could >> eliminate SORTWK DD? >> >> If the programming team are not convinced, does this look right, based on >> the discussion - and based on a 100% Disk sort, which is not likely? >> 450mill * 110 * 1.5 = 74250000000 = 69GB so maybe SORTWK01 - >> SORTWK10 >> //SORTWK01 DD UNIT=WORK,DSNTYPE=LARGE,SPACE=(CYL,(4000,1000)) >> to >> //SORTWK10 DD UNIT=WORK,DSNTYPE=LARGE,SPACE=(CYL,(4000,1000)) >> >> and this will give me 4000 + (15*1000) on each, or 40000c primary + >> (up to 150 * 1000) secondary >> >> While we have been talking here, I have looked, and found some jobs >> with >> //SORTWK01 DD UNIT=(WORK,5)... >> and this will not work, is that right, Sri Kolusu? I would only get the >> first volume anyway? >> >> Thank you and best regards, >> Billy Ashton >> >> >> ------ Original Message ------ >> From "Farley, Peter" >> <0000031df298a9da-dmarc-requ...@listserv.ua.edu> >> To IBM-MAIN@listserv.ua.edu >> Date 7/3/2023 12:44:43 PM >> Subject Re: SORTWK space usage >> >>> I will add on to Sri's excellent answer with my very STRONG recommendation >>> NOT to use hard-coded SORTWK's in your JCL. Both of the major SORT vendors >>> (IBM and Syncsort) do a far, far better job of estimating necessary SORTWK >>> space and memory utilization than any human could hope to do. >>> >>> I also STRONGLY recommend that you give your JCL and program-controlled >>> SORT steps as much memory in the REGION parameter as your installation >>> allows for production and test jobs. Both of the major SORT programs will >>> figure out how much of that memory to use, whether and how much of it to >>> use in the current WLM environment, and will make VERY effective use of as >>> much of it as they can to cut down on SORT execution and elapsed time. >>> Memory is (relatively) cheap, don't be afraid to use all you've got >>> available to shorten your SORT times. >>> >>> My basic advice is don't try to second-guess these very intelligent >>> programs - they each have more than half a century of practice and >>> experience that none of us can match, even those of us who have been around >>> that long. >>> >>> Peter >>> >>> -----Original Message----- >>> From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On >>> Behalf Of Sri h Kolusu >>> Sent: Monday, July 3, 2023 12:28 PM >>> To: IBM-MAIN@LISTSERV.UA.EDU >>> Subject: Re: SORTWK space usage >>> >>>>> I will only get the primary space of 5000 cylinders, and the other >>>>> 14x2000 cylinders is never used. Is that right? >>> >>> Billy, >>> >>> No. Incorrect. DFSORT will make use of BOTH primary and secondary space >>> allocations ( 1 primary + 15 Secondary) for a total of 16 extents. So if >>> you allocated 1 sortwk dataset with (CYL,(5000,2000)), then DFSORT would >>> use 5000 + 15* 2000 = 5000 + 30000 = 35,000 cylinders. Also note that the >>> secondary extents will only come into picture ONLY when needed. >>> >>>>> Is there a written explanation I can forward to the programmers so they >>>>> understand this? >>>>> Also (since I know it will come), is there any good way to calculate how >>>>> much DASD sortwork would be used? I know this depends on what is in >>>>> memory at the time, but want to get a better handle on how Sort >>>>> determines what it needs. >>> >>> I would suggest that you use DFSORT's Dynamic Allocation as it will >>> allocate the required workspace optimally rather than programmers >>> calculating it. The reason is you don't want to change the allocation >>> every time there is an increase/decrease in the number of records to be >>> sorted. >>> >>> Having said that, here is a general formula that you want to use. >>> >>> The amount of sortwk space required depends on the size of the file. It >>> usually ranges from 1.3X to 1.8X of the size of the file to be sorted >>> depending on the sorting path that DFSORT chose. >>> >>> Filesize = Number of records * Avg length of the record ( for Fixed >>> length RECFM=F or FB , it is the LRECL value, or RECFM=V or RECFM=VB >>> is the average length of the record) >>> >>> However, that range is applicable ONLY when the entire file is being >>> sorted using Disk workspace. DFSORT has the capability of using memory >>> (real and auxiliary storage) and if it runs out of it, it will then use >>> disk workspace. >>> >>> >>> Thanks, >>> Kolusu -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
