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Sarangadhar · Posted: Mon Nov 01, 2004 7:36 am Post subject: CISZ size calculation

Hi I got CISZ size calculation from some book.
Assume Rec len=1000, CISZ=4096:

Then these 4096 are allocated as below:
1.Reserve 10B for control info. 10
2.Reserve 20% of assigned CISZ for FREESPACE(4096*.20) 819
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Total 829
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3.Remaining space in CISZ =4096-829=3267
4.Devide this by RECLEN(1000) to get no. of records for CI 3
5.Remainder 267

So this 267 bytes of space is unusable.

Is this calculation is correct?
And as per this calculation 4th record inserted in another CI as 267B is not enough to hold 1000B reclen. So we need to reorganize VSAM dataset once we for more CIs, right?
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Thanks

modak · Beginner Joined: 09 Apr 2004 Posts: 14 Topics: 3

You calculation is correct. you need not worry about reorganization of VSAM. This is taken care by CI/CA split. 267 byte is a waste . Only thing that you can do is organize your CI such that this unused space is less. and most of the books I have reffered indicates that 4096 byte size is good for CI.