-----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Paul Gilmartin Sent: Tuesday, May 05, 2015 8:11 AM To: [email protected] Subject: Re: IEFBR14 question
On Tue, 5 May 2015 07:46:33 -0500, John McKown wrote: > >> But it's inappropriate that the OS create a new data set when it knows >> that it will be deleted immediately, never used. > >Is it "inappropriate"? Suppose, just for the sake of argument, that I am >an clever JCL coder. I know that all the NEW allocations for permanent data >sets in the job will amount to some number of cylinders. Now, I don't want >the job to fail some steps into the job due to lack of disk space. So what >I do is create a initial IEFBR14 step which allocates some number of >permanent DSNs of appropriate size with DISP=(NEW,DELETE). What I am >hoping is that if sufficient space is _NOT_ available, that I will get a >JCL error very early in the processing, rather than later. > One might make the same argument against bypassing HRECALL, yet the IBM designers have chosen to bypass. -- gil A couple possible reasons for the difference. Orders of magnitude difference in time needed to satisfy the request - milliseconds to allocate and deallocate a (MOD,DELETE,DELETE) versus needing to mount a physical tape to do a recall - especially one that may not be in a library. Relative frequency of an allocation going against a migrated dataset versus the increase in code length needed to check every allocation for the combination of (MOD,DELETE,DELETE) and IEFBR14. Different design teams. Complexity of the code change needed for HSM recall bypass versus bypassing allocation altogether for this particular combination. Rex ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] 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 [email protected] with the message: INFO IBM-MAIN
