On Mon, 27 Feb 2017 06:47:14 -0500, John Eells wrote:
>Paul Gilmartin wrote:
>
>> http://i2.kym-cdn.com/photos/images/original/000/475/756/7ab.jpg
>>
>> ... what the users wanted was a PARM on the EXEC statement longer than 100
>> bytes.
>> Somehow, IBM couldn't understand.
><snip>
>
>We certainly *did* understand. We further understand that there were
>sound reasons why that was not done. In fact, there was a protracted
>discussion right here in IBM-MAIN about how we should implement this
>support, well in advance of its actual appearance, led by the designer.
>I am reasonably confident that you can find in that discussion why it
>was done as it was, if you care to look.
>
You're suggesting that a transcript or summary of those discussions
is available. Can you cite? Thanks.
Those discussions were protracted. Two or three decades ago a colleague,
not then an IBM employee, was party to an RFE for longer PARM. IBM
rebutted him with an alternative similar to PARMDD. I suspect implementation
was deferred until DD DATA,SYMBOLS= and in-stream data sets in
PROCs became available.
I try to envision a rationale. If a longer PARM is cumbersome for internal
operations, it could be cached in a spool file, but transparently to the user.
Otherwise, compatibility is not preserved. A program that follows (non-GUPI?)
control blocks to find PARM is broken alike by PARMDD or by restructuring
control blocks to relieve the 100-character constraint.
in: SA23-1385-03 z/OS MVS JCL Reference
Chapter 16. EXEC statement
PARMDD parameter
Record length requirements
... Fixed record length data sets and in-stream data sets are examined to
determine
if their records contain sequence numbers. ...
So, apparently, variable record length in-stream data sets are processed for
sequence numbers. Other variable record length data sets are not.
Why? This is puzzling. I'll submit an RCF.
Thanks again,
gil
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