This is a pure guess on my part. I don't known how BPAM works internally.
But I do know that in a standard PDS, there are multiple entries in each
physical directory block record on disk. So I am wondering if what is
happening is that STOW reads __and buffers__ the directory block you're
working on, and then defers rewriting the directory block. This _might_
cause the 2nd job to have an out of date buffer for a physical directory
block record which happens to contain your old STOW data. When the 2nd job
gets around to flushing the data to disk, it would implicitly replace what
your 1st job had done in the directory.

Just a WAG.

On Sun, Jul 19, 2015 at 8:07 AM, Binyamin Dissen <[email protected]
> wrote:

> I have code that does the following: (against a standard PDS)
>
>          ENQ
>          OPEN
>          BLDL
>          POINT TTR
>          READ
>          CHECK
>          WRITE  (in place)
>          CHECK
>          STOW R  (changing some directory info of the rewritten member))
>          CLOSE
>          DEQ
>
>
> When running single threaded, works fine.
>
> When running in multiple concurrent jobs, it appears that sometimes the
> STOW
> data is lost.
>
> GTF trace shows that the code is operating properly.
>
> What might II be missing?
>
> --
> Binyamin Dissen <[email protected]>
> http://www.dissensoftware.com
>
> Director, Dissen Software, Bar & Grill - Israel
>
>
> Should you use the mailblocks package and expect a response from me,
> you should preauthorize the dissensoftware.com domain.
>
> I very rarely bother responding to challenge/response systems,
> especially those from irresponsible companies.
>
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-- 

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Maranatha! <><
John McKown

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