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rasprasads · Posted: Thu Apr 10, 2003 12:20 pm Post subject: Empty file allocation

I created an empty file with the following step:

Bithead · Posted: Thu Apr 10, 2003 1:22 pm Post subject:

Why would you use SORT to allocate an empty file when IEFBR14 will do it?

Why would you want a file of this size with nothing in it?

Bill Dennis · Posted: Thu Apr 10, 2003 1:40 pm Post subject:

Bithead,
Allocating with IEFBR14 has it's drawbacks since it does not OPEN/CLOSE the file to create a valid EOF pointers.

rasprasads,
Are you aware of the JCL subparameter RLSE for allocations? Read about it in the the Fine JCL manuals under the SPACE paramter.

Bill

kolusu · Posted: Thu Apr 10, 2003 2:19 pm Post subject:

Rasprasad,

'K' indicates that the primary and secondary space quantity specified by the SPACE= parameter represent the number of records to allocate space for, in K (1,024 record multiples).

In your examples, a primary quantity of 300K (307,200) records, and a secondary quantity of 450K (460,800) records.

You will have 7050 cylinders(300+15*450) with an allocation of SPACE=(CYL,(300,450),RLSE) which will allow you to copy approximately 60,000,000(60 million records)

Check the following thread in JCL forum where it explains the space calculation for the datasets based on the LRECL and volume of records.

http://www.mvsforums.com/helpboards/viewtopic.php?t=28

Personally I would direcly copy to the target dataset instead of creating an empty dataset and then copying the data.

Hope this helps...

cheers

kolusu

semigeezer · Posted: Thu Apr 10, 2003 4:18 pm Post subject:

Allocation now takes care of the EOF marker, so automatic allocation (eg: IEFBR14) should be fine.

rasprasads · Posted: Thu Apr 10, 2003 11:59 pm Post subject:

The file i am going to create will be loaded by the users. So i have created an empty file and just wanted to know about the no.of records that can be loaded to an empty file.

Kolusu thanks for your valuable info.....
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Rasprasad S

rasprasads · Posted: Fri Apr 11, 2003 12:10 am Post subject:

Kolusu,

I have also this doubt...

warp5 · Posted: Fri Apr 11, 2003 12:38 am Post subject:

Rasprasad, he multiplied the secondary value by the max. amount of extents (a total of 16, that means 15 secondary extents) to show the max size of the dataset. After data has been put into it and the dataset is closed the RLSE will release any unused space.

rasprasads · Posted: Fri Apr 11, 2003 3:55 am Post subject:

Ok !!!
Thanks Warp5. You gave me the correct idea.
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Rasprasad S