On Thu, 17 Jul 2008 02:21:29 -0500, William H. Blair wrote:
>
>But, 42 years of experience with IBM tells me that this is how
>it is going to be, so I'm going to have to find some other way
>of "hiding" in-stream data sets. (You're not the only one to
>use this technique. It's not unheard of. I've seen it in many
>"production" JCL streams. Other folks are going to get burned
>by this, but I have no clue how many. I would hope not many.)
>
I have long been in the habit of using:
//HIDDEN DD * (text to be ignored)
All the unprocessed text
that I want.
I think this makes my intent far more clear than relying on your
convention of using an undeclared SYSIN as a collateral comment. I
consider the latter irresponsibly lazy and lacking in referential
transparency. It's redolent of trying to assure one's job security
by writing incomprehensible code.
>I wonder if anybody at IBM even thought about the possibility
>that this slick new feature might break existing customer JCL.
>Probably not. They probably got an award just for their bright
>idea. Oh, well.
>
Whine, whine, whine! JCL has sucked for those 42 years. This
has frequently been attributed in this forum to resource constraints
in those early systems. Now advancing technology has relieved those
constraints and IBM is DTRT in making JCL infinitesimally closer to
what it should have been from the beginning. Hooray! It's similar
to USERKEYCSA -- some things that have to be fixed should be fixed.
I'd be glad to see more changes for robustness and clear reporting
of user errors. E.g.:
o Duplicate DDNAMEs within a step should be treated as a JCL error.
(I understand JES3 already does this.) This itself would have
blocked the pitfall described in this thread.
o The "SYSIN DD * GENERATED STATEMENT" behavior should be removed
from the language. The last time I encountered this, I had
inadvertently left a '/' off a JCL statement (perhaps a comment)
before my actual intended SYSIN. The utility then saw an empty
SYSIN. Took me far too long to spot. At least there should be
an option such as GENSYSIN(YES|NO) on the JOB statement. I'd
use NO.
o All the usages described in the JCL manual as having "unpredictable"
effects should be reported as JCL errors (or those with repeatable
behaviors documented).
Perhaps a conversion utility should be provided to tidy up legacy
careless JCL.
-- gil
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