"Recommendation: After you activate SMS, select temporary data sets for migration to system-managed storage. Managing temporary data sets during this phase of the implementation enables you to gain experience with DFSMS functions. Temporary data sets are easy to identify and recreate, and do not require availability management. The following are benefits of system-managed temporary data sets: Both temporary VSAM and non-VSAM data sets are supported. Temporary data sets are automatically deleted by DFSMShsm, thus supporting efficient space management. Temporary data sets left by the system because of abnormal end-of-job are deleted by DFSMShsm during space management.
Temporary data sets can be allocated on VIO or system-managed storage volumes. Using system-managed temporary data eliminates the need for dedicated public or temporary volumes, and frees volumes for permanent data sets. Temporary data sets can be directed to VIO based on data set size and usage, improving performance by directing I/O to your processor's central or expanded storage. VIO data sets are backed by auxiliary storage as paging data sets. Temporary data set access to VIO can be restricted, based on the RACF® variables, &USER and &GROUP. RACF-related ACS READ/WRITE variables, &USER and &GROUP, can be interrogated in your ACS routine to limit access to VIO. Temporary data sets are created and deleted within the same job, job step, or terminal session. No entries are made in the basic catalog structure (BCS) for these data sets, but system-managed VSAM data sets do have VVDS entries. Both VSAM and non-VSAM data sets have VTOC entries. The data set name for temporary data is either omitted or is a single qualifier with && or && at the beginning. When the DSNAME is omitted, the system generates a name that begins with SYS and includes the Julian date and time. When you code request temporary data set allocation, the ACS read-only variable data set type, &DSTYPE, is set to TEMP. The storage class ACS routine determines whether to allocate these data sets to VIO or to volumes in a pool storage group category depending on the data set usage and size. During automatic space management, DFSMShsm automatically deletes system-managed temporary data sets that remain on a volume after an abnormal end of job or system failure. Figure 1 shows how DFSMShsm allocates and manages temporary data sets." -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 עַם יִשְׂרָאֵל חַי ________________________________________ From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> on behalf of Jon Perryman <jperr...@pacbell.net> Sent: Friday, November 24, 2023 12:57 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: UNIX REXX LINKMVS TASKLIB? On Fri, 24 Nov 2023 00:10:18 +0000, Seymour J Metz <sme...@gmu.edu> wrote: >if you insist on using VOL=SER=foo for a temporary, it will work. Cleanup of the public volumes is unpredictable. Normal users should never learn about VOL=SER especially for temporary datasets. > IMHO, it's best to let SMS do its thing. Unless things have changed, SMS does not control temporary datasets. The system places them on volumes mounted public or storage bypassing the need for SMS. ---------------------------------------------------------------------- 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
