On Wed, 13 Feb 2008 13:03:24 -0600, Kenaan Tabikh wrote:
>Is anyone aware of a JCL parameter that enhances 3590 tape stacking
>performance? Maybe something in DATACLAS? I was told about this but
>cannot find anything. Maybe DCB=OPTCD=?
>
>Thanks,
>
>Ken Tabikh
I think you might be referrring to High Speed Positioning, which was introduced
in OS/390 R7 by APAR OW49828 back in 2001. From that APAR:
----------------------------------------
File stacking write performance gain requires no application changes.
Applications that write multiple files on the same tape, in the same job and
that specify a volume disposition that leaves the cartridge positioned at the
end of each file created will experience significant performance improvement.
This occurs when any of the following are true.
1. CLOSE macro is issued with the LEAVE option.
2. RETAIN is coded in the JCL volume parameter and CLOSE is issued with DISP
parameter coded or defaulted.
3. PASS is coded in the JCL disp parameter.
This will save several seconds of real time for each file
created.
----------------------------------------
There are more details regarding this enhancement in the APAR.
Brian
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