On Mon, 22 Jul 2013 09:08:12 -0700, Ed Jaffe wrote: >A customer (mildly) complained thatsome of our product allocations still >use BLKSIZE=3120. I vaguely remember trying to change all of them to >BLKSIZE=0 many years ago (probably before OS/390) and running into some >issues with certain IBM utilities. Unfortunately, I can't remember the >specifics. > >In starting to revisit this again, I noticed numerousoccurrences of >'3120' in IBM help and documentation. For example, the TSO/E RECEIVE >command HELP claims that the log data set must be BLKSIZE=3120: > Is there any difference between explicitly specifying BLKSIZE=0 and simply omitting BLKSIZE? Except in COBOL?
A War Story: Long prior to the advent of SDB, I had formed the habit of omitting BLKSIZE in my Rexx EXECs. The Rexx function library was smart: it chose good BLKSIZEs and/or I didn't much care about fractional deviations from absolute optimality. And, for all I knew (and didn't care) it adapted well to different device types. Suddenly I started getting Sx13 in old debugged EXECs. It seems that Rexx had deferred BLKSIZE selection to SDB, and SDB was doing a poorer job of selecting BLKSIZE than Rexx. In fact, it was (as then documented!) selecting BLKSIZE=80 for all subsystem data sets (JES and UNIX). RECFM=VBA,LRECL=137, BLKSIZE=80 worked poorly. But when I reported the problem, IBM had the fix at hand. Worked. But IBM warned me: o The repair was designed for JES, and was not certain to work for UNIX files. (Worked OK.) o The repair necessarily violated the _published_ specification of BLKSIZE=80, and if another customer complained, it might be necessary to revert it. o I was advised to stop deferring BLKSIZE and specify it explicitly in all my code. Considerably ironic that a consequence of SDB was that I was advised not to rely on it. (It's better now.) Is there any hope that COBOL will come to trust SDB when BLKSIZE is omitted, or would that necessarily entail a standards violation? -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
