Hmm. I *may* need to take back what I said. It looks like for XMIT I specify 27920 but it forces 3120. Would need to do more research and no time at the moment.
I *know* I tell customers to allocate a file 27920, upload from the PC, and run RECEIVE against it, so I know that works -- or at least I am not getting customer complaints. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of R.S. Sent: Monday, July 22, 2013 10:18 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: BLKSIZE=3120 W dniu 2013-07-22 18:08, Ed Jaffe pisze: > 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: > > <TSO/E RECEIVE command HELP> > LOGDATASET You may specify an alternate data set to be > used for the logging of the transmitted data. > This data set will be created if it does not > exist. The data set should be created with > a logical record length of 255, a record format > of VB and a blocksize of 3120. > ... > > LOGDSNAME You may specify an alternate data set to be > used for the logging of the transmitted data. > This data set will be created if it does not > exist. The data set should be created with > a logical record length of 255, a record format > of VB and a blocksize of 3120. > </TSO/E RECEIVE command HELP> > > Is this just outdated help? Or does this restriction still exist? > > is z/OS still a "mine field" filled with subtle dependencies on > BLKSIZE=3120? > Well, IMHO it's not restriction, it is just allocation default. Good default in very old days, but not very bad today. Note, The difference between ~3k and optimal ~27k seem to be large, but the effects (performance, space used) give no big difference. BTW: DB2, LOGGER, MQ, and many many VSAM exploiters do use blocks 4kB. Is it far from 3kB? Of course you can try the above datasets with other (SDB) blocksize, and I bet nothing will break. Why didn't they change it? Well, it time to re-start the following subthreads: - TSO is moribound - if it isn't broken don't fix it (see latest implementation as IMBED for catalogs). ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
