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
