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Set ACB parameter for a VSAM file

 
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Magesh_J
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Joined: 21 Jun 2014
Posts: 259
Topics: 54

PostPosted: Thu Sep 21, 2017 6:05 pm    Post subject: Set ACB parameter for a VSAM file Reply with quote

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
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kolusu
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Joined: 26 Nov 2002
Posts: 12358
Topics: 75
Location: San Jose

PostPosted: Fri Sep 22, 2017 11:13 am    Post subject: Reply with quote

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
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Kolusu - DFSORT Development Team (IBM)
DFSORT is on the Web at:
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Magesh_J
Intermediate


Joined: 21 Jun 2014
Posts: 259
Topics: 54

PostPosted: Fri Sep 22, 2017 1:05 pm    Post subject: Reply with quote

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
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kolusu
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Joined: 26 Nov 2002
Posts: 12358
Topics: 75
Location: San Jose

PostPosted: Fri Sep 22, 2017 11:28 pm    Post subject: Reply with quote

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
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Kolusu - DFSORT Development Team (IBM)
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Magesh_J
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Joined: 21 Jun 2014
Posts: 259
Topics: 54

PostPosted: Tue Sep 26, 2017 6:27 pm    Post subject: Reply with quote

Thanks Kolusu, Will check with System programmer.

Regards,
Magesh
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