On Tue, Dec 8, 2015 at 3:05 PM, Paul Gilmartin <
[email protected]> wrote:

> On Tue, 8 Dec 2015 14:30:25 -0500, Robert A. Rosenberg  wrote:
>
> >At 10:29 -0700 on 12/08/2015, Paul Gilmartin wrote about Re: Inquire
> >intrdr default job class:
> >
> >>ISPF EDIT has some effective techniques for serializing updates to
> >>PDS members, precluding two programmers' editing the same member
> >>simultaneously.
> >
> >Does the ISPF EDIT support take into account that the "Same Member"
> >means the same PDS not just any PDS with the same name but different
> >volumes? Using the PDS name without qualifying it with the VOLSER
> >where it resides is the same problem/design-flaw which ENQ on SYSDSN
> >has since it leads to False Positive errors claiming the resource is
> >in use due to not bothering to take into account the volume where a
> >dataset resides.
> >
> I wonder whether IBM knows about that.
>
> -- gil
>
>
>
​The "flaw" exists:
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/ispzpc90/APPENDIX1.1.3
<quote>
APPENDIX1.1.3 Member name enqueue


To restrict concurrent use of a member of a partitioned data set, while
still allowing ISPF users to use different members of the same data set
(PDF EDIT, Table Processing, File Tailoring), ISPF issues this ENQ macro
for the member:

           ENQ SPFEDIT,rname,E,52,SYSTEMS

where

rname
​     ​
the data set name, length of 44, padded with blanks, followed by the member
name, length of 8, padded with blanks
</quote>​


​I do not really agree that not including the volser in the SYSDSN enqueue
is a "flaw". If it were done, then their could need to b​e multiple ENQs,
one for each volume in a multi-volume DSN. Also, when a DSN is extended to
another volume, then an new SYSDSN ENQ would need to be issued. This could
possibly fail, although I would think it unlikely. But remember this was
designed in OS/360 and "set in stone" back when it would cost much more,
relatively speaking, in CPU and main memory overhead. Once "set in stone",
changing it is very difficult. Not only to code & test, but to put up with
customers who could start screaming about needing to change their code to
be compatible.



-- 

Schrodinger's backup: The condition of any backup is unknown until a
restore is attempted.

Yoda of Borg, we are. Futile, resistance is, yes. Assimilated, you will be.

He's about as useful as a wax frying pan.

10 to the 12th power microphones = 1 Megaphone

Maranatha! <><
John McKown

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