Hi Skip,
I found this blurb about RECLAIMCA in the DFSMS book "AMS for catalogs" at the
1.13 level under the ALTER section:
<quote>
RECLAIMCA|NORECLAIMCA Specifies the CA reclaim attribute of a key-sequence
data set (KSDS).
RECLAIMCA Specifies that the DASD space for empty control areas (CAs) will
be reclaimed so that it can reused for that KSDS. CA reclaim cannot reclaim
space for:
Partially empty CAs
Empty CAs that already existed when CA reclaim was enabled
CAs with RBA 0
CAs with the highest key of the KSDS
Data sets processed with GSR.
NORECLAIMCA Specifies that the DASD space for empty control areas (CAs)
will not be reclaimed. You can disable CA reclaim at the system level with
the IGDSMSxx member of PARMLIB or with the SETSMS command. This does not change
CA reclaim attributes in the catalog. For more information, see the topic
about reclaiming CA space in z/OS DFSMS Using Data Sets.
</quote>
The comment in the doc about disabling CA reclaim not changing the reclaim
attribute in the catalog lends credence to your comment about the ALTER command
being accepted and turning it on/off even though CA reclaim isn't active.
HTH,
Rex
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Jesse 1 Robinson
Sent: Thursday, September 29, 2016 4:03 PM
To: [email protected]
Subject: Re: VSAM CA reclaim for RMM
Correcting ALTER syntax.
-----Original Message-----
From: Jesse 1 Robinson
Sent: Thursday, September 29, 2016 1:59 PM
To: 'IBM Mainframe Discussion List' <[email protected]>
Subject: Re: VSAM CA reclaim for RMM
Thanks. Spent some time this morning wading through the doc. Here's a thumbnail
version of my understanding.
-- CA reclaim must be 'turned on' at the system level in PARMLIB IGDSMSxx.
Default value is 'off'.
-- It can also be turned on or off for a system with a SETSMS command.
-- Once turned on globally, CA reclaim will be in effect for (more or less)
every VSAM cluster unless a cluster is specifically turned off. That is, the
default at the cluster level is on. My RMM control data set is 'on' as shown by
LISTCAT.
-- You can turn a cluster off or back on with a simple ALTER command--which BTW
I cannot find documented anywhere except in KC discussions of CA reclaim. For
example, I cannot find any reference to reclaim in TSO HELP for ALTER.
-- The IDCAMS command is "ALTER entry-name RECLAIMCA/NORECLAIMCA". That command
is accepted now when I enter it even though we do not have reclaim turned on
globally.
So if you turned reclaim on for 'some user catalogs' and for SMS control data
sets, did you take any action to turn it off for everything else in the house?
.
.
J.O.Skip Robinson
Southern California Edison Company
Electric Dragon Team Paddler
SHARE MVS Program Co-Manager
323-715-0595 Mobile
626-302-7535 Office
[email protected]
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf
Of Mike Schwab
Sent: Thursday, September 29, 2016 12:57 PM
To: [email protected]
Subject: (External):Re: VSAM CA reclaim for RMM
We had some user catalogs needing annual reorgs. Control Area Reclaim
eliminated this. Helped with SMS control data sets and ML1 Small Data Set.
Don't know about user datasets.
On Thu, Sep 29, 2016 at 11:08 AM, Jesse 1 Robinson <[email protected]>
wrote:
> (In honor of today's post from Mike Wood.) We don't make much (if any) use of
> CA reclaim here. It occurs to me that RMM might be an excellent candidate. We
> periodically have to reorg the data base-sometimes when RMM crashes in the
> middle of the day.
>
> When CA reclaim was first presented at a closed SHARE session on a Sunday
> morning, there was great interest in the room but also some skepticism. What
> is the current consensus on CA reclaim? How extensively is it implemented
> these days? Recommendations?
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