They say that the memory is the second thing to go (I don't remember the first.) IEFBR14 with DDDISP=(,PASS) or DISP=(,CATLG) does allocate a new data set. there would be much wailing and gnashing of teeth if it stopped doing that.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of CM Poncelet <[email protected]> Sent: Wednesday, August 7, 2019 12:34 PM To: [email protected] Subject: Re: CPU time cost of dynamic allocation >From years ago, I *think* an IEFBR14 step with DISP=(,CATLG) [or (,PASS)] does not physically allocate a dataset on a VOLSER but only registers it in the usercat. Have you checked whether it is in the VTOC? Chris Poncelet (retired sysprog) On 06/08/2019 20:38, Charles Mills wrote: > FWIW I tried adding DISP=(,PASS) to all of the DDs and adding another (BR14 > also) step. No difference in the step CPU time -- still 0.00 seconds. > > Of course, one could play guessing games all day. Is the Initiator smart > enough to know the whole job is one big no-op? I would guess not, but who > knows. > > Charles > > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Paul Gilmartin > Sent: Tuesday, August 6, 2019 12:45 PM > To: [email protected] > Subject: Re: CPU time cost of dynamic allocation > > On Tue, 6 Aug 2019 12:25:05 -0400, Charles Mills wrote: >> OTOH I have an IEFBR14 batch job on the same machine that allocates 15 >> temporary datasets in JCL. The entire job lock, stock and barrel uses >> (according to IEF032I) .00 CPU seconds. Can anyone explain why JCL >> allocation is apparently much more CPU efficient than SVC 99 allocation? >> > Nowadays, z/OS performs some special optimization for IEFBR14 (it knows > it's not going to use those data sets anyway.) Might that come into play > here? > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > . > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
