Joel's right, of course, that I meant "RECFM=U, when used for load
modules." (I must say, though nothing prohibits using RECFM=U for some
other purpose, that I have yet to see it actually done!)
Joel C. Ewing wrote:
Knowing John's background, I would suspect he may have intended to state
"For RECFM=U, 32760 MAY indeed BE optimum", or perhaps intended to
restrict the remark just to load libraries. I believe all the arguments
in the archives for using block size 32760 with RECFM=U on 3390 were
specifically directed to datasets that are used for Load Libraries.
While this is probably the most common usage for RECFM=U, there is
nothing to disallow other usage of RECFM=U; and those other
applications, unlike program management, might not be smart enough to
utilize shorter blocks to effectively utilize a DASD track.
I agree that it has been established that BLKSIZE 32760 makes sense for
a RECFM=U load library on a 3390. But, a RECFM=U data set that is not a
load library would not necessarily meet the additional requirement of
containing a combination of long and short blocks, which as John states
is a necessary condition for a block size greater than half-track to
have any chance of decent track utilization on a 3390.
Joel C. Ewing
<snip>
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
ee...@us.ibm.com
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