That really depends on the RECFM and, for variable blocked RECFMs, the
distribution of block sizes. For RECFM=U, 32760 is indeed optimum
(search the archives for why), and for some (not necessarily common)
distributions of variable blocks it might well use space better than
half track blocking. Anything that writes a combination of long and
short blocks can yield surprising results. (We found that z/OS fonts,
for example, use the least space at a counterintuitive block size.)
For plain old sequential FB data, though, it's quite right that 32K is a
poor choice of block size.
Bill Fairchild wrote:
3390 full track size is ca. 56K, and 3380 is ca. 47K. But you were right - 32K
is still not optimal for 3390.
<snip>
--
John Eells
z/OS Technical Marketing
IBM Poughkeepsie
ee...@us.ibm.com
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