On Tue, 12 Sep 2017 15:40:16 -0500, Tom Marchant wrote:
>>> 
>>What does a relative generation number greater than +1 mean? 
>
>If you create a Generation Data Set with JCL using +1 in one step, 
>and want to refer to it in a subsequent step in the job, you 
>reference it as +1. If you want to create another GDS for the same 
>GDG, you would specify +2.
>
OK.

If a job uses +2 but never mentions +1, is an error reported?
What if the step that creates +1 is skipped by COND or IF?

>In a subsequent job, assuming no other GDS created for that GDG, 
>these same data sets would be -2 and -1.
>
Then I'd have expected -1 and 0.  But I'm often wrong.  Fencepost errors and 
all.

On 2017-09-12, at 14:30, Feller, Paul wrote:

>I think someone mentioned WAD.  If I remember correctly when using the +1 the 
>system does an enqueue on the BASE as part of the process.  The enqueue is not 
>release until the file is closed.  I believe this is done to insure proper 
>"roll in" of the new generation.
>
"CLOSE"d or "FREE"d?

>I believe this same behavior happens when you are reading a GDG by the +1 or 
>+0 or whatever.  Any new allocation of the GDG will fail or hang until the 
>other job closes the file it is reading.  For reads I have gotten around this 
>by doing the allocation using the full dataset name.
>
Would that not also work for writes?  Or can a generation be written only once?

The OP mentioned BPXWDYN.  Can the "full data[ ]set name" be found by
BPXWDYN(INFO ...) or BPXWDYN( ALLOC RTDSN(...) ...)?

-- gil

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