> -----Original Message-----
> From: IBM Mainframe Discussion List On Behalf Of Farley, Peter x23353
>
> > -----Original Message-----
> > From: IBM Mainframe Discussion List On Behalf Of Clark Morris
> <Snipped>
> > On 30 Apr 2009 13:00:02 -0700, in bit.listserv.ibm-main you wrote:
> >
> > Try TRUNC(OPT). Trunc STD would require the conversion to decimal
to
> > guarantee that the data fit the picture. TRUNC(BIN) is known and
> > documented to generate less than optimal code.
>
> Son of a gun, that did it. From half a page of code to six
> instructions.
>
> I will have to test this program with TRUNC(OPT) pretty carefully to
> make sure it has no other adverse affects. The doc on OPT is pretty
> clear in its warnings.
>
> And the doc on TRUNC(BIN) does have the phrase "... you can avoid the
> performance overhead of using TRUNC(BIN) ...", implying there is, in
> fact, a performance penalty for using it.
>
> Thanks for pointing out the benefit of TRUNC(OPT) to me.
But then there's this in the "Notes" for TRUNC in the Installation &
Customization Guide:
" 2. TRUNC=BIN is the recommended option when interfacing with other
products that have S/390-format binary data (such as CICS, DB2, FORTRAN,
and PL/I). This is especially true if there is a possibility of having
more than 9 digits in a fullword or more than 4 digits in a halfword."
So, we're stuck with TRUNC(BIN) in CICS, where arguably we'd want the
"best" performance. :-(
-jc-
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