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What does the "optimize" parm do?
Question:
really would like to know what exactly does the 'Optimize' parameter of the Generation Options on the crtpgm or chgpgm command does optimize.
I remember that 4 or 5 years ago I once experimented with it, putting the pgm parameters of our most used programs in production on Optimize, and as a result our machines went crazy and lazy...
Not much of an optimisation was done.
Probably there are many 'optimisations' performed on the parameter, so , wath would it do now, either on a OPM or on a ILE pgm .
Our machines are on V3R7 and V3R6 (will be upgraded to 7).
Answer(s):
"Optimize" does a lot, but it can only speed up program execution, not
disk I/O, etc, so there may or may not be a significant improvement if you
use it.
While it is theoretically possible for "optimization" to make performance
worse, in practice this doesn't happen to any extent. (There are some
programs that are "hard to optimize", and these may end up being 1-2%
worse, but they are rare.) When optimization works well (best on large
programs without a lot of calls), the improvement can be 4:1 or better
(though this is also rare). Typical results would be 30% to 50% reduction
in CPU time.
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