One idea might be to change the DATACLAS as follows: set column 14 'VOLUME 
COUNT' to '1' and then set column 16 'DYNVOL COUNT' to '58'.

This prevents the catalog record from containing unused fields for DASD volumes 
never allocated since only the volumes actually used will be contained in the 
catalog.

However, this does use extra space in the TIOT. (Suggestion: Set TIOT size to 
64 in the ALLOCxx PARMLIB member.) Even with TIOT size 64, JOBSTEPs with over 
125 or so DD cards all specifying this DATACLAS will blow out the TIOT and the 
job will fail.

-----Original Message-----
From: IBM Mainframe Discussion List <[email protected]> On Behalf Of 
Jousma, David
Sent: Friday, April 4, 2025 9:21 AM
To: [email protected]
Subject: Migrating Storage pools to EAV

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So, we are finally biting the bullet and making 1TB EAV volumes our standard 
for UCB relief, etc.    One "habit" my Storage team over the years had done to 
mask poor dataset allocations was to make the mainly used DATACLAS 
multi-volume, with a max of 59 volumes.    It was before my time, but I'm 99% 
sure that was done to avoid x37 abends for max extents.    Now that we are 
going to EAV's, we'll be clearing off the mod-54's and DISNEW them.   And with 
a 20-1 reduction in physical volumes, there will likely be pools that had say 
100 volumes, that could end up with just 5 EAV's.

I'm not a storage guy by craft, so am wondering if there is any magic dust to 
help with this other than making the owners of the poorly allocated files make 
adjustments to their allocations?

Dave Jousma
Vice President | Director, Technology Engineering


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