Estimating the size of a VSAM file

Pratheep · New User Joined: 20 Mar 2005 Posts: 3 Location: singapore

Hi,
Our cics regions have files defined with lot of space without considering the reqrment, so that now we are running short of DASD space. So I would like to redefine/reorganize all the files.

Now, my question is how to estimate the optimized primary/secondary spaces reqd for these files.
For example I have a file 'abc' with record length 3850 and having 1 million (10,00,000) records in it. So the file size may be = (rec len x no.of records)/bytes per cylinder.
So i will get the space needed for the file in cylinder unit (file size).
Now, assume I give x/y as the primary/sec space in cylinders for the file. So the size will be x + (y x 123), (which is the no, of extends).

Now which will be the most optimized way to decide x and y.?

Assume I will give freespace(20,20). CISize(8192)

Can somebody help me.. eagerly looking for some answers... don't worry about the example above. its only a sample for you to understand the problem. Real thing is how to estimate.

sivatechdrive · Posted: Mon Mar 21, 2005 4:27 pm

Hi Pradeep

there is a vsam spacer tool available with mainframe cd which may help you.

Check the below site this may help you

www.circle4.com/jaqui/pouvsm92/pouvsm92.html

Thanks
Siva

Pratheep · New User Joined: 20 Mar 2005 Posts: 3 Location: singapore

Hi Siva,
Thank you very much for the detailed document. I am sure this will help me.

What I am doing now is, i got another tool for calculating the file size in cylinders. And the information i got from various sources so far, says that, deciding primary and secondary most optimized spaces is not possible with tools or formulae.
So I am in the process of deciding the most optimized size for each files by looking at the size, type and growth rate of the files.

Anyway, thank you very much for the information provided. It really good.

Regards
Pratheep

somasundaran_k · Active User Joined: 03 Jun 2003 Posts: 134

Pratheep
You can download free VSAM space caluculator from here.
www.talsystems.com/tsihome_html/techcorner.html

hth
-Som

Pratheep · New User Joined: 20 Mar 2005 Posts: 3 Location: singapore

Hi Som,
Thanks for the reply.

This is the same link as Siva provided.

Thanks again

Pratheep