IBM Mainframe Forum

by **Viswanathchandru** » Fri Sep 28, 2012 5:27 am

Dear all,

Is there a way to alter the GDG limit without the Generations getting deleted/rolled off?. Please point me through some manual if the answer is yes. Apologize if I or my thoughts are wrong!

Regards,
Viswa

by **dick scherrer** » Fri Sep 28, 2012 6:27 am

Hello,

Suggest you post the gdg definition and how many generations are currently in use.

Then explain how you want to alter the gdg limit.

by **Viswanathchandru** » Fri Sep 28, 2012 6:33 am

Hello Dick Scherrer,

Thanks for addressing the post!

I have defined a gdg of this kind through the IDCAMS with the below control cards:

DEFINE GDG( -
NAME(xxxxx.GDG.BASE) -
LIMIT(05) -
NOEMPTY -
SCRATCH)

Now, when i do a alter against this GDG base with the control card:

ALTER SYS3VCT.GDG.BASE LIMIT(02)

I'm getting (ideally it should) the first three generation files getting rolled out/deleted. But, what i'm asking is, Is there a way we can alter the GDG limit without loosing the Generation files?

Regards,
Viswa

by **steve-myers** » Fri Sep 28, 2012 6:47 am

You can increase the limit, but to lower the limit you must delete or rename the appropriate datasets before you attempt to change the limit.

by **dick scherrer** » Fri Sep 28, 2012 7:16 am

Hello,

If you want to reduce the limit, why keep the "discards"?

If they are worth having, why lower the limit?

by **Robert Sample** » Fri Sep 28, 2012 7:20 am

From the manual AMS For Catalogs (called VSAM Services for DFSMS in the Manuals link above):

LIMIT(limit)
Used to modify the maximum number (between 1 and 255) of active generation data sets (GDSs) that might be associated with a generation data group (GDG) base.

limit
If the limit is less than the current number of active generations, the oldest generations are rolled off until the new limit is satisfied. Any GDSs that are rolled off by this command are listed showing their new status (recataloged, uncataloged, or deleted). For more information about limit processing of a GDS, see z/OS DFSMS Managing Catalogs.

If the limit is greater than the current number of active generations, it does not cause the roll-in of existing rolled off GDSs. For this function, see the ROLLIN parameter.

In other words, if you alter the limit below the number of existing generations of the GDG, the oldest generations are rolled off -- period. You cannot change this behavior.

by **Monitor** » Fri Sep 28, 2012 10:51 am

Coding NOSCRATCH tells that you want to keep the datasets physically and rolled-off generations can still be referenced by their full names.
The LIMIT() just tells how many generations to be kept cataloged. When the LIMIT() is reached SCRATCH/NOSCRATCH tells what to do with the rolled off's.

by **Viswanathchandru** » Fri Sep 28, 2012 2:39 pm

Hello Robert, Monitor thanks for addressing the post!

yes, Even i tried the same of doing a NOSCRATCH and the Generation was removed from the catalog and i was no more be able to access the rolled off GDG's. I tried to ROLLIN the uncatalogued and it ended with error saying "Not eligible for ROLLIN".

Select all

Coding NOSCRATCH tells that you want to keep the datasets physically and rolled-off generations can still be referenced by their full names.

Can we still access the Generation that was kept on NOSCRATCH ? I was not able to do it.

Regards,
Viswa

by **Monitor** » Fri Sep 28, 2012 2:49 pm

The old generations are not cataloged. You must know the vol=ser to see/ref them ( what I remember!)

by **Viswanathchandru** » Fri Sep 28, 2012 4:01 pm

Hello Monitor,

Thanks for addressing the post! Yes, I tried with Volume name in ISPF 3.4 and tried doing a browse and its says dataset not catalogued.

Regards,
Viswa

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