Hmm, didn't think of using CRTE etc, since I was fixated on CLFITxx 
instructions. The immediate value is a halfword, so you can code a lot more 
variations of the CLFIT instruction to uniquely identify which specific 
instance produced the S0C7.

Robert Ngan
HCL

P.S. I always seem to code the CLFIT instruction wrongly, since it is the only 
variation of the COMPARE AND BRANCH/JUMP/TRAP that requires the F, and I keep 
forgetting the F (although I do understand why the F was added for it).

-----Original Message-----
From: IBM Mainframe Assembler List <[email protected]> On Behalf 
Of Jonathan Scott
Sent: Monday, August 6, 2018 12:20
To: [email protected]
Subject: Re: EX

Robert Ngan writes:
> Not sure why no one has mentioned the COMPARE AND TRAP type
> instructions, in
> most(?) cases they'll do the test and force the abend when required.

If you have to write product code that still works for CMS users in ESA mode, 
then COMPARE AND TRAP is not an option.  It needs
z10 or above, which I think is part of the architectural level set required by 
z/OS 2.2 so if you are on that level or above it is safe to use.

> My only gripe is there's no extended mnemonic for an unconditional
> TRAP when there's no appropriate "compare" (e.g. I need to do a TM).

I've never used it myself, but I think the simplest way to code an 
unconditional trap is to use CRTE 0,0 or similar, using two references to the 
same register which are certain to compare equal.

Jonathan Scott, HLASM
IBM Hursley, UK

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