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John Young
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Joined: 22 Aug 2011
Posts: 2
Location: USA
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I have been trying to allocate a VSAM data set of an exact size, with 10 cylinders primary, and 5 cylinders secondary.
The resulting allocation (from LISTCAT) indicates primary of 23 cylinders and a secondary of 12 cylinders.
The data set IS SMS managed.
It appears SMS is making a decision to increase the allocation. Can the allocation be influenced to make it the specified size? |
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Robert Sample
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Joined: 06 Jun 2008
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Location: Dubuque, Iowa, USA
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| Discuss the problem with your site support group. SMS policies can override JCL allocations, and it may -- or may not (depending upon the site -- be possible to change the actual allocation. |
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Bill Woodger
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Joined: 09 Mar 2011
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Location: Inside the Matrix
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enrico-sorichetti
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Joined: 14 Mar 2007
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Location: italy
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John Young
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Joined: 22 Aug 2011
Posts: 2
Location: USA
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Yes, I saw the information about extent consolidation, but the difference in the specified space, and the actual allocation are before any data has been loaded into the file.
Our ACS routines do not make any changes to the allocation parameters. |
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enrico-sorichetti
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Location: italy
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hard to believe... IT is pretty deterministic
and software is usually pretty dumb, it does only what it is told to do  |
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vasanthz
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Joined: 28 Aug 2007
Posts: 1742
Location: Tirupur, India
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Hi,
| Quote: |
with 10 cylinders primary, and 5 cylinders secondary.
The resulting allocation (from LISTCAT) indicates primary of 23 cylinders and a secondary of 12 cylinders. |
Maybe you are specifying the space in 3380 device and SMS allocation exit is configured to allocate in 3350 device type.
In this case,
5 cylinders on JCL would result in 12 cylinders allocated.
10 cylinders on JCL would result in 24 cylinders allocated.
math:
5 cylinders * 15 = 75 tracks.
3380 track size * number of tracks = 47476 * 75 = 3,560,700 (total size)
round down(Total size / 3350 track size) = round down(3560700/19069) = 186 tracks.
round down(186 tracks / no of tracks per cylinder) = round down(186 / 15) = 12 cylinders allocated.
Similarly,
10 cylinders * 15 = 150 tracks.
3380 track size * number of tracks = 47476 * 150 = 7121400 (total size)
round down(Total size / 3350 track size) = round down(7121400/19069) = 373 tracks.
round down(373 tracks / no of tracks per cylinder) = round down(373 / 15) = 24 cylinders allocated.
Disclaimer: I myself don't trust my math. Verification of above is recommended. |
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enrico-sorichetti
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Pete Wilson
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Joined: 31 Dec 2009
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Location: London
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The CI and CA freespace values can affect the allocation size significantly. What have you specified for this file?
When you say it has become 23cyls is that immediately after defining the cluster or has it been loaded wih data?
Check the Dataclas assigned to the file as well, it may have overriding space values set. You can check the Dataclas values in ISMF option 4 |
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