Hi list,
I had a strange one thrown to me from a developer and I'm hoping somebody can
point me to something to explain why this is happening. Environment is z/OS
2.4 and Cobol 6.3,pretty vanilla. I've read through SDB explanations in
several manuals but haven't found the explanation as to why this is happening.
We have a Cobol program with record length 200, and the developer inadvertently
omitted the BLOCK CONTAINS 0 RECORDS clause which according to the Cobol
manual says the file is supposed to be unblocked. Developer runs the program
in batch using a DD card like this for the unblocked dataset.
//VSF DD DSN=TEST.DATASET.NAME,
// DISP=(NEW,CATLG,DELETE),
//* UNIT=VTS,
// UNIT=SYSDA,
// SPACE=(CYL,(5,20),RLSE),
// DCB=MDCB.TEST.DATASET.NAME
The only DCB information provided is in the MDCB statement which looks like
this:
% XT Device Dsorg Recfm Lrecl Blksz
----------------------------------------------
MDCB.TEST.DATASET.NAME
0 ? 0 3390 FB 200 0
Sorry for the lack of formatting, BLKSIZE=0, LRECL=200, RECFM=FB.
If he runs his job with the DD card as above, going to an SMS managed dataset,
he gets half track blocking. If he runs it changing it to UNIT=VTS, he gets an
unblocked dataset, and if he runs it against DASD with an unmanaged dataset
name, he also gets it unblocked. Definitely makes it look like something in
the SMS configuration, however, our SMS dataclas that this dataset falls under
does not specify to use SDB that I could find. So my questions are how to
explain what's happening here? Why does the MDCB specification of SDB seem to
override the Cobol program in the case of the SMS managed dataset but the Cobol
program overrides the MDCB for the non-SMS datasets?
TIA,
Rex
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