On 6/30/2010 9:16 PM, Shmuel Metz (Seymour J.) wrote:
And it would be interesting to determine whether
the common practice of updating a PDS with a primary ENQ of SHR has
led IBM to add format 1 updates to the STOW logic.
I doubt it; they don't permit concurrent OPEN for update.
Rather than argue, I decided to run a quick test. I allocated a
PDS with one directory block, linked one member, inspected the
DSCB, ran a second link step with two members, but having the
last include a member from a (forced) unready pack, allowing the
DSCB to be inspected after the link for member 2, and before
member 3. After the first link, the DS1NOBDB field is 49, and
DS1LSTAR is 00000A. After the second link, the format 1 has not
changed; after the third link, it shows DS1LSTAR as 00001A and
DS1NOBDB as 121. DISP was SHR for all libraries. So STOW may set
information in storage, but only a CLOSE (or TCLOSE) will update
the DSCB.
So long running tasks with a shared PDS would be advised to
close it before issuing the secondary (link or ISPF) enqueue,
and reopen to update.
Gerhard Postpischil
Bradford, VT
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