[EMAIL PROTECTED] wrote: > In a recent note, Greg Price said: > > >>Date: Wed, 1 Jun 2005 14:16:51 +1000 >> >>Well, here's my theory: >> > > Does this have to be done by theory and/or experiment, or is it made > clear in the documentation?
I believe theory/experiment/doco all agree on how "the system" behaves here. The "theory" reference is due to me not having access to the current source of IEBGENER. I'd say your outline of the SYSUT2 DCB Open exit (which need bear no similarity to the exit for SYSPRINT) sounds pretty right. I was going to suggest that experiments with SYSOUT are not relevant to illustrate DCB processing, but Ed J said it first. Hence my passing remark about a "real line printer". Allocating a real unit record device takes the dummied up DCB facade of JES ACB processing out of the picture. IOW, I was trying to think of a device where QSAM/BSAM could be used that was not TAPE or DASD to illustrate a currently available non-SDB example. Programs that will abend with S013-34 when the output file is on TAPE or DASD will often not abend when the output is directed to SYSOUT because of its forgiving nature. I haven't done much JES3, but JES2 does not seem to care about DCBBLKSI remaining zero at all (it still remains zero after OPEN whereas SDB will put a non-zero value in it). I have not checked the doco re your point about the exit getting control before or after the SDB is filled in. Experiment indicates that the exit ends before the OPEN-time SDB is supplied. Therefore, a run-of-the-mill IEBGENER step can produce different output blocksizes depending on something as simple as whether DSORG=PS is specified in the JCL or not. It's been a while, but IIRC I used to have ACS routines which set DSORG=PS for DASD data sets whenever a null DSORG was found at creation time. For data sets that were never opened this used to allow recognition that they were empty as well as HSM migration. But yes, if the DCB blocking has been determined by the user or by allocation-time SDB, IEBGENER's DCB Open exit has nothing to do about setting the output blocksize. My "surmise" about allocation-time SDB is really just me parroting back the publicity around at the time SDB was introduced. Since behaviour matched what I was told I've never checked the manuals on it. I expect "DFSMS: Using Data Sets" to talk about the OPEN-time SDB, and "DFSMS: Implementing System Managed Storage" (SC26-7407-02) to talk about the DADSM end of things including allocation-time SDB. I suppose it might be nice if each had a pointer to the other if they don't already. Cheers, Greg ---------------------------------------------------------------------- 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
