On Thu, Apr 3, 2014 at 12:54 PM, John McKown
<[email protected]>wrote:

> ISPF option 3.4, doing a "z" on a PDS to compress it will result in a
> DISP=OLD type allocation. This is the only thing that _I_ know of which
> does this.
>
>
Oh. How this is relevant to this scenario is if the user was editing a
member in the PDS and tried to save it. At this point, the DSN is allocated
and ENQ'd with a DISP=SHR. The user gets an Sx37 abend because the PDS is
out of space. So s?he splits the screen, goes into option 3.4, does a "z"
to compress the PDS. At this point, ISPF "upgrades" then already existing
ENQ on the already allocated PDS from a SHR to an OLD. Remember that the
user still has the DSN allocated in EDIT on the other screen. The compress
finishes. Until z/OS 2.1, it was _impossible_ to "downgrade" from an
exclusive ENQ (DISP=OLD) back to the shared ENQ (DISP=SHR). So the DSN is
now allocated to the user with a DISP=OLD until such time as it is freed.
Which may __OR MAY NOT__ happen when the user exits the EDIT on the member.

-- 
There is nothing more pleasant than traveling and meeting new people!
Genghis Khan

Maranatha! <><
John McKown

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