bpxwdyn() is just a text-interface to SVC99.   I don't believe that z/OS
Unix System Services is related at all.

Kirk Wolf
Dovetailed Technologies
http://dovetail.com

On Tue, Sep 12, 2017 at 1:10 PM, Steve Thompson <[email protected]> wrote:

> The way I read this, z/UNIX is enqueing on the GDG base while it does its
> work. And I can't tell from what is provided how long it holds that before
> it frees it.
>
> Regards,
> Steve Thompson
>
>
> On 09/12/2017 01:24 PM, Paul Gilmartin wrote:
>
>> On Tue, 12 Sep 2017 11:54:04 -0500, Kirk Wolf wrote:
>>
>> Is there a way around this?
>>>
>>> Even with SMS-managed GDGs, where the generation is cataloged at
>>> allocation, two jobs that dynamically allocate +1 generations (with
>>> GDGNT)
>>> will collide.
>>>
>>> For example, from two different jobs:
>>>
>>> (job 1)
>>> ./bpxwdyn.rexx "alloc fi(mydd) da('managed.test.gdg(+1)') recfm(v,b) new
>>> catalog gdgnt lrecl(1028)"
>>> BPXWDYN RC= 0  (0x0)
>>>
>>> (job 2)
>>> ./bpxwdyn.rexx "alloc fi(mydd) da('managed.test.gdg(+1)') recfm(v,b) new
>>> catalog gdgnt lrecl(1028)"
>>>
>>> BPXWDYN RC= 34603008  (0x2100000)
>>> IKJ56225I DATA SET MANAGED.TEST.GDG ALREADY IN USE, TRY LATER+
>>> IKJ56225I DATA SET IS ALLOCATED TO ANOTHER JOB OR USER
>>> IEFA110I DATA SET CONTENTION
>>>
>>> It feels as if Allocation fails to perform some needed serialization.
>>
>> Might this be APARable?
>>
>> How large is the hazard window?  Does it extend beyond the activity of
>> SVC 99?
>>
>> Is it holding an ENQ on the GDG base even after allocating the new
>> generation?
>>
>> Do batch job behave similarly?  I suppose one might wait for initiation
>> until
>> the earlier one DEQs.
>>
>> Why are you doing this?  It looks like a race where it doesn't matter who
>> wins.
>>
>> Does a similar problem exist for generated DDNAMEs ("SYSnnnn") among
>> multiple concurrent tasks in a single job?
>>
>> -- gil
>>
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