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Increase Control Interval Size of VSAM file

 
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nelson.pandian

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Joined: 09 Apr 2008
Posts: 133
Location: Phoenix, AZ

PostPosted: Thu Mar 04, 2010 10:48 am    Post subject: Increase Control Interval Size of VSAM file
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Hi Experts,

I'm going to increase the Record size of a VSAM file from 1500 to 2000. Do i need to increase Control interval size? I have given the current definition of the VSAM file below.

Code:
DEFINE   CLUSTER -                   
    (NAME(<VSAM File name>)) -       
DATA (NAME(<VSAM File name.DATA>) -   
     CISZ(16800)        -           
     CYL(275 25) -                   
     FREESPACE(18 8)     -           
     SUBALLOCATION -                 
     SHAREOPTIONS(2 3) -             
     KEYS(15 0)         -           
     RECORDSIZE(65 1500) -           
     VOL( * * * )) -                 
 INDEX (NAME(<VSAM File name.INDEX>) -
     CISZ(2048)   -                 
     SHAREOPTIONS(2 3) -             
     SUBALLOCATION -                 
     VOL( * * * ))                   

This is a KSDS and we will be using Sequential & Random read and fill file sweep. There will be 10-15 Million records in the file for processing. Please suggest me that do i need to increase control interval size, free space, cylinder size or any other stuff.
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dick scherrer

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Joined: 23 Nov 2006
Posts: 19270
Location: Inside the Matrix

PostPosted: Thu Mar 04, 2010 11:05 am    Post subject:
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Hello,

Suggest you do some reading here:
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/handheld/Connected/BOOKS/DGT2D460/2.5.1
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Pete Wilson

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Joined: 31 Dec 2009
Posts: 437
Location: London

PostPosted: Thu Mar 04, 2010 4:01 pm    Post subject:
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Your current CISIZE should be OK, but the Data CI FSPC% would be better set to 12 so the freespace in each CI would be big enough to contain a 2000byte record. I've put an example here of various CISIZES and the number of minimum or maximum record sizes that would fit in each. You want the nearest to a perfect fit if possible, and any freespace should be enough to contain an additional maxlrecl record. (I only show the data ci fspsc here) If your file Your CISIZE can be any multiple of 512 up to half track maximum. Not sure why you have CA fspc set to 8. This shouldn't be necessary unless you have a huge number of inserts, and if your data ci fspc is correct there shouldn't be too many data ci splits to cause ca splits. In terms of file size, it can be between 1Gb and 30Gb based on the min or max lrecl's and 15m records, so you should size according to that. How you achieve that in primary or secondary sizes depends a bit on your local setup of the Dataclas (if applicable). Your currrent allocation only provides for 0.23Gb primary and 0.02Gb secondary so I'd suggest that could be increased considerably.

CISIZE 16800 27648 26624 8192

MinLrecl 65 258.46 425.35 409.60 126.03
MaxLrecl 2000 8.40 13.82 13.31 4.10

fspc 18 8 3024 4976.64 4792.32 1474.56
fspc 12 8 2016 2211.84 2129.92 983.04
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