You can continue to use R15, if you really must. And it should work if you do put the return code and modifer (both!) in the DSA area.
John McKown Systems Engineer IV IT Administrative Services Group HealthMarkets® 9151 Boulevard 26 . N. Richland Hills . TX 76010 (817) 255-3225 phone . [email protected] . www.HealthMarkets.com Confidentiality Notice: This e-mail message may contain confidential or proprietary information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. HealthMarkets® is the brand name for products underwritten and issued by the insurance subsidiaries of HealthMarkets, Inc. -The Chesapeake Life Insurance Company®, Mid-West National Life Insurance Company of TennesseeSM and The MEGA Life and Health Insurance Company.SM > -----Original Message----- > From: IBM Mainframe Assembler List > [mailto:[email protected]] On Behalf Of Frank Swarbrick > Sent: Tuesday, June 12, 2012 4:20 PM > To: [email protected] > Subject: Re: CEETERM and register 15 > > So it sounds like the original author should have never used > R15 in the first place for the base register. OK. > > The program doesn't use any macros other than the CEE ones I > just added and ABEND. But I'll see if I can find a free > register other than 14 (or 15 or 0 or 1!). It's pretty much > used every other register at some point in the program, but > hopefully I can get around that. > > I've been reading about "baseless" programming and all new > code I've added uses it, but at this point it don't want to > make too many changes to it. So is your suggestion to use > RC=RETCODE,MODIFIER=MOD and have those two as part of my > automatic storage area? Actually, if I do that I can > probably get away (for now) with leaving it using R15, since > those fields will be based on R13. > > I will try this out. Thanks for your help!!!! > Frank > > > > > >________________________________ > > From: "McKown, John" <[email protected]> > >To: [email protected] > >Sent: Tuesday, June 12, 2012 2:53 PM > >Subject: Re: CEETERM and register 15 > > > >The reason for the L in CEETERM is because you can do > CEETERM RC=VARNAME,MODIFIER=MODNAME where VARNAME and MODNAME > are fullword areas. > > > >In general, in z/OS, you should __never__ use R0 (impossible > actually), R1, R14, or R15 for a CSECT/RSECT base register. > Many (most) IBM macros use these registers. And occassionally > other registers as well. > > > >For LE enabled assembler (I have written some), when I use a > base register at all (not often any more), I use R11 for my > first, then R10, R9, and so as as the module grows in size. > In "modern" programming, you can avoid the use of a "base > register" for code in almost every case by using relative > instructions instead of based instructions. E.g. use LARL > instead of LA for areas in the CSECT, and Jxx instead of Bxx > for branching. If you load constant values, try to use LHI if > possible. Do try to write reentrant code. If you do that, you > can keep the modifiable values in the DSA, which is addressed > by R13 and which is set up for you with the CEEENTRY and > CEEDSA macros. For a constant which does not fit into a > halfword, or maybe is packed decimal or characters, you can > replace somethin like: L R7,FULLWORD with 2 instructions: > LARL R7,FULLWORD followed by L R7,0(,R7), and the same with > packed and characters. OK, that is a bit ugly, I admit. > > > > > >-- > >John McKown > >Systems Engineer IV > >IT > > > >Administrative Services Group > > > >HealthMarkets® > > > >9151 Boulevard 26 . N. Richland Hills . TX 76010 > >(817) 255-3225 phone . > >[email protected] . www.HealthMarkets.com > > > >Confidentiality Notice: This e-mail message may contain > confidential or proprietary information. If you are not the > intended recipient, please contact the sender by reply e-mail > and destroy all copies of the original message. > HealthMarkets® is the brand name for products underwritten > and issued by the insurance subsidiaries of HealthMarkets, > Inc. -The Chesapeake Life Insurance Company®, Mid-West > National Life Insurance Company of TennesseeSM and The MEGA > Life and Health Insurance Company.SM > > > >> -----Original Message----- > >> From: IBM Mainframe Assembler List > >> [mailto:[email protected]] On Behalf Of > Frank Swarbrick > >> Sent: Tuesday, June 12, 2012 3:25 PM > >> To: [email protected] > >> Subject: CEETERM and register 15 > >> > >> First off please realize that I'm an assembler beginner. > >> I've fiddled with it here and there for 15 years, but I'm > >> really just a COBOL programmer. So please be gentle! :-) > >> > >> We have a vendor written, code supplied, subroutine that does > >> for us a few things that COBOL can't (bit fiddling; posting > >> of an ECB; etc.). This same exact routine is called both by > >> batch COBOL program and CICS COBOL programs. It is not > >> reentrant. In order to make it reentrant I have been working > >> on "LE-enabling" it. This seems to work quite well! But I > >> ran in to something "weird" with CEETERM. CEETERM RC=0 > >> generates the following: > >> > >> 58F0 F098 013A0 1827+ L 15,=A(0) > >> > >> 5800 F098 013A0 1828+ L 0,=A(0) > >> 58DD 0004 00004 1829+ L 13,4(13) > >> 58E0 D00C 0000C 1830+ L 14,12(,13) > >> 981C D018 00018 1831+ LM 1,12,24(13) > >> 07FE 1832+ BR 14 > >> > >> Problem? The program uses register 15 as the base register. > >> Funny thing is that the code actually "works". But it really > >> doesn't. The first L sets R15 to 0. Then the second L loads > >> in to R0 from 152(,R15), but of course R15 is now 0, not the > >> real base address it needs to be. It's only coincidence that > >> 152 bytes in to low core contains x'00000000'. If I tried to > >> use an RC of some other value it would still be set to 0. > >> > >> > >> I changed the program to use 14 instead of 15 for the base > >> register and all is now fine. But I don't see it documented > >> that CEETERM should not be used when the base is R15. Or is > >> it just common practice to not use R15 as the base? Other > >> than this one program I don't see that R15 is generally used > >> for that purpose even though it starts out with the correct > >> address, which is probably why it was used in this case. > >> Specifically, the original code was this: > >> SUBR CSECT > >> > >> USING *,RF > >> B START > >> DC CL8'SUBR' > >> START DS 0H > >> SAVE (14,12) > >> > >> Anyway, I have to wonder why CEETERM doesn't take a page from > >> the RETURN macro, and use LA from an offset into "R0", i.e., > >> if I had CEETERM RC=12,MODIFIER=8, we'd get something like this: > >> > >> LA 15,12(0) > >> LA 0,8(0) > >> L 13,4(13) > >> L 14,12(,13) > >> LM 1,12,24(13) > >> BR 14 > >> > >> No base register needed, correct? (This is one of those > >> cases where "register 0" is really just "zero", right, no > >> matter what value it actually holds?) > >> > >> > >> (Apologies to Russ Evans, if he is reading this, for taking > >> an unexpected side trip to LE land.) > >> > >> Hope I've not shown too much ignorance. > >> > >> > >> Thanks! > >> Frank > >> > >> > >> > > > > > > > >
