Hmmm. I had understood that this works only if DSORG is known.
But the wording appears back to the oldest OS/390 doc I find on
publibz. And note that the mechanism is not described. It could
be by writing an EOF at the beginning; it could be that a flag is
set (in the DSCB?) to indicate that the data set is uninitialized.
Note that it mentions GET and READ, but not EXCP. And it does not
mention any PARMLIB option.
It is done by writing an EOF on the first track at the time the dataset
is allocated. There is no option to control this. Most JCL allocates
sequential datasets without specifying DSORG (the DSORG is not
determined until the dataset is opened for output), so IBM decided to do
this for all SMS datasets with DSORG=PS or null.
They could have easily done this for non-SMS as well, but I guess they
opted for "compatibility".
--
Bruce A. Black
Senior Software Developer for FDR
Innovation Data Processing 973-890-7300
personal: [EMAIL PROTECTED]
sales info: [EMAIL PROTECTED]
tech support: [EMAIL PROTECTED]
web: www.innovationdp.fdr.com
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