On Thu, 6 Jul 2006 12:58:50 -0500, Ed Gould <[EMAIL PROTECTED]> wrote: > > >> The SAMe SU (IIRC) assumed that all blocks would be the same size > >> except for the last. I don't recall of finding short blocks in any of > >> the QSAM type datasets sine the SAMe came out. I don't recall of a > >> programmer ever needing a short block. While there may b e a few out > >> there I have never run across them personally. > >> > > It has long been possible to create interior short blocks by at > > least the following techniques: > > > > o RECFM=V > > > > o DISP=MOD > > > > I doubt that SAMe would have had the influence to change either > > of those. > > > > -- gil > Gil, > > WHile that is true no programmer I ever ran into, ever trusted > "MOD" . Yes it does work though. The programmers really only use of > mod was in checkpoint restart tape. Even then it was grimaced at. > Back in the "old times" uptime was at best bad (can we say 5 > minutes?) so no one really trusted it (MOD). > This is the first I have heard of unreliability of DISP=MOD. Is that the consensus of readers here?
That said, my most frequent uses of MOD are for its collateral effects: o Conditionally create a data set in an IEFBR14 step with DISP=(MOD,CATLG), then write it in a subsequent step with DISP=OLD. o Conditionally delete a data set with DISP=(MOD,DELETE). o DISP=MOD,DSN=HLQ.LLQ(&MEMBER) to prevent overwriting an existing member. I've distributed some JCL using this, and about once a year I get a phone call about a Sx14 ABEND. Generally, the caller is grateful when I remind him he was about to overwrite, and renames the existing member for backup. -- gil -- StorageTek INFORMATION made POWERFUL ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
