Woohoo, I finally said something on IBM that is of benefit to someone else. I think I will take the rest of the day off. I'm batting 100%, and I don't want to screw that up.
-----Original Message----- From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Pommier, Rex Sent: Thursday, May 12, 2022 10:07 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: [EXTERNAL] Re: Potential Resource Savings Techniques [External Email. Exercise caution when clicking links or opening attachments.] 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. 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