Alan Altmark wrote:
On Thursday, 02/25/2010 at 05:03 EST, Ivan Warren <[email protected]>
wrote:
Basically, I believe HCPCFC (which is OCO.. Yuck !) simply looks at the
length of the command passed, verifies it doesn't exceed the length of
the command and then does an EX/CLC for the abbreviation for the command
to check for a match - which means no difference in processing time
between an abbreviation and a fully spelled out command. That how it was
done in my time in DMKCFC anyways.
My point it that I strongly believe there is no difference in CP
processing time for an abbreviated CP command.
Leaving specific instructions out of it, yes, that's how it works.
Compare this to any readability issues - a second over a year of
processing time compared to an hour by a human being trying to figure
out why it's not the right command being issued !
And we DO change abbreviations sometimes. When we introduced the FOR
command, it was necessary to change the abbreviation of FORWARD from FO to
FORW.
Always spell out your CMS and CP command names AND operands in order to
avoid such gotchas. Abbreviations are for humans, not programmers.
Alan Altmark
z/VM Development
IBM Endicott
The gory details escape me now, but we had a customer
application at IGS that issued a *lot* of CP commands.
Customers complained of poor response time so we consulted
with Development and were advised that in that particular
situation we should abbreviate CP commands for improved
performance.
We were doubtful but coded an old vs. new test and timed
their performance (both Virtual and Elapsed) on our lightly
loaded Customer Production cpu at 2am on a Sunday when we
had a maintenance window and customers couldn't log on.
The results confirmed what Development had said, so we
retested on our highly loaded Dev system during prime time
and the resulting difference was obvious.
That was sometime long before my retirement in May 2004 and
was a *very* unusual case. Generally, I would always use
the fully spelled out CP command.
Les
