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Size to Alocate

 
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Elixir

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Joined: 08 Feb 2009
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Location: CHENNAI/NEW JERSEY - INDIA/USA

PostPosted: Thu Oct 27, 2011 9:13 pm    Post subject: Size to Alocate
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Hello,

thru rexx is it possible to before hand know the size to alocate for a ps/pds?

thanks!
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enrico-sorichetti

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Joined: 14 Mar 2007
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Location: italy

PostPosted: Thu Oct 27, 2011 9:21 pm    Post subject: Reply to: Size to Alocate
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YES ...
if You know the sizes of things that have to be contained in it
- number of members
- number of record

YES if You know the formulas and how to write REXX


otherwise the answer is NO/NO
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Elixir

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PostPosted: Thu Oct 27, 2011 9:30 pm    Post subject:
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1 CYL = 15 TRKS
1 TRK = 56, 664 BYTES
if you define the LRECL as 56664, then one record is stored in each track.
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enrico-sorichetti

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PostPosted: Thu Oct 27, 2011 9:34 pm    Post subject: Reply to: Size to Alocate
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Quote:
f you define the LRECL as 56664, then one record is stored in each track.

NO...

look at the manuals for the blksize and lrecl constraints

look at the stickies in the ispf part of the forums for a blocks per track calculator I wrote .
http://www.ibmmainframes.com/viewtopic.php?t=55037
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Pedro

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PostPosted: Thu Oct 27, 2011 10:51 pm    Post subject: Reply to: Size to Alocate
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Besides the device geometry information, you really need to know how many members and how many records will be contained.

A somewhat lazy* approach is to allocate a large dataset and also specify the RELEASE parameter. After writing your records and closing the file, the unused space is released.

* I am somewhat lazy myself.
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Robert Sample

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Location: East Dubuque, Illinois, USA

PostPosted: Fri Oct 28, 2011 1:42 am    Post subject:
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From the JCL Language Reference manual section 12.42.2 on LRECL in the DD statement, available at the Manuals link at the top of the page:
Quote:
The value of bytes is:

1 to 32,760 for non-VSAM data sets.

1 to 32,761 for VSAM key-sequenced (KS), entry-sequenced (ES), or relative record (RR) data sets. (LRECL does not apply to VSAM linear space, RECORG=LS, data sets.)

Elixir, perhaps you want to revise this statement in light of the manual?
Quote:
if you define the LRECL as 56664, then one record is stored in each track.
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