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maverick05 · Beginner Joined: 15 May 2005 Posts: 72 Topics: 24

Hi,
I have unloaded a DB2 table with many variable columns into a flat file.
I believe the max size of the data in flat file can be found by multiplying total records and max logical record length.Any idea how to calculate the exact size of a flat file ?

papadi · Advanced Joined: 20 Oct 2009 Posts: 520 Topics: 1

There is no need to "calculate" the size. Once created it is fixed/known.

Using tso/ispf 3.4, look at the "info" for the file.

You might also look into using LISTDSI.

Once you get the "exact size" how will this be used?
_________________
All the best,

di

Nic Clouston · Posted: Mon Jul 30, 2012 12:19 am Post subject:

I do not know about this but perhaps your unload job provide some statistics inclding bytes unloaded?
_________________
JCL is a means by which the programmer makes known to the computer the resources required by the program to be executed and certain characteristics of these resources.

maverick05 · Beginner Joined: 15 May 2005 Posts: 72 Topics: 24

papadi · Advanced Joined: 20 Oct 2009 Posts: 520 Topics: 1

kolusu · Posted: Mon Jul 30, 2012 10:50 am Post subject: Re: Flat file size

taltyman · Posted: Thu Aug 02, 2012 7:53 am Post subject:

I'm guessing here since you aren't posting enough information but...

this is a variable record length flat file format

you take the longest record length and multiply it by the number of records to come up with your max size statement

now you want to really know the exact size as determined by bytes or whatever actually used, not how much space it actually needed as reported by 3.4 and then line option I?

In over 30 years of mainframe experience I've never seen a need for this kind of information. Tell us what you are trying to accomplish

maverick05 · Beginner Joined: 15 May 2005 Posts: 72 Topics: 24

William Collins · Beginner Joined: 03 Jun 2012 Posts: 123 Topics: 0

With the 32K blocksize, you will have a lot of empty space on each track. So your file will occupy more tracks, more cylinders. Your file will be "bigger" in terms of cylinders, but will contain the same amount of data.

With the optimal blocksize, the file will be considerably smaller, in terms of using fewer cylinders.

maverick05 · Beginner Joined: 15 May 2005 Posts: 72 Topics: 24

papadi · Advanced Joined: 20 Oct 2009 Posts: 520 Topics: 1

No. Space allocated will differ but the bytes of user data will remain the same.
_________________
All the best,

di

maverick05 · Beginner Joined: 15 May 2005 Posts: 72 Topics: 24

Nic Clouston · Posted: Mon Aug 13, 2012 10:44 pm Post subject:

I do not understand why you would think that you would have more data just because the data set size is different because of different block-sizes! Di you think that you would get some free data?
_________________
JCL is a means by which the programmer makes known to the computer the resources required by the program to be executed and certain characteristics of these resources.