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#1: Set ACB parameter for a VSAM file Author: Magesh_J,

Posted: Thu Sep 21, 2017 6:05 pm
—
Hi,

Please advise, how do i change/set ACB parameter for vsam dataset in batch.

Example :

Code:

//VSAM1 DD DSN=VSAMDATA,DISP=SHR,AMP=('ACCBIAS=SW')

For above vsam dataset, i need to set MACRF=(NSR,SEQ,DIR,OUT,SKP)

How do i set it or where do i set this option.

Thanks
Magesh

#2: Author: kolusu, Location: San Jose

Posted: Fri Sep 22, 2017 11:13 am
—
Magesh_J,

With ACCBIAS=SW you are already getting SEQ,SKP

If you want both Direct access and sequential access of records change it to ACCBIAS=DW

Look up Table 14. SMB access bias guidelines in z/OS DFSMS Using Data Sets Here

http://publibz.boulder.ibm.com/epubs/pdf/dgt3d410.pdf

Read Chapter 10. Optimizing VSAM Performance

#3: Author: Magesh_J,

Posted: Fri Sep 22, 2017 1:05 pm
—
Thanks Kolusu for the kind response.

All i need is make my program/jcl use NSR buffer instead of LSR

When we specify AMP=('ACCBIAS=DW') It switches to LSR resulting in performance problem.

When i specify AMP=('BUFND=39,BUFNI=139') , It is running very good.

But the problem is BUFNI will always varies based on the calculation

Code:

BUFNI = TI - (HURBA / CASIZE) + STRNO

All I need is AMP=('ACCBIAS=DW') and NSR Buffer.

I see following program in the book, but not sure how to write or where to write and how to invoke for my vsam file.

Code:

START CSECT
SAVE(14,12) Standard entry code
.
B INIT Branch around file specs
MASACB ACB DDNAME=MASDS,AM=VSAM, File specs X
MACRF=(KEY,SEQ,OUT), X
EXLST=EXITS, X
RMODE31=ALL
END

Thanks
Magesh

#4: Author: kolusu, Location: San Jose

Posted: Fri Sep 22, 2017 11:28 pm
—
Magesh_J,

You need to have a dataclass that supports SMB. Talk to your systems programmer and have the VSAM dataset in a dataclass with SMB

#5: Author: Magesh_J,

Posted: Tue Sep 26, 2017 6:27 pm
—
Thanks Kolusu, Will check with System programmer.

Regards,
Magesh

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