And for those exits that must be RMODE 24 all you really need is a little stub in BTL storage that upgrades its AMODE and branches to the real exit logic. The advantage is that you do not need a "real" AMODE 24 load module; you get just GETMAIN the BTL storage and move a few bytes of code into it.
Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Greg Price Sent: Saturday, November 16, 2019 11:03 PM To: [email protected] Subject: Re: In what context/amode BSAM/BPAM READ with SF64 On 2019-11-17 5:40 PM, Joseph Reichman wrote: > I normally do all I/O in amode 24 because of the EODAD of AL3 the open > having an AL3 for the DCB Unless you have an old ESA or even older XA system, there's no need to do I/O in amode24 these days. Just use amode31. The AL3 pointers will restrict you to rmode24, but that's a different story. If the only DCB exits you use are EODAD and/or SYNAD, and you want to go rmode31 (or rmodeany if you prefer) then you can supply their 4-byte address in the DCBE macro. But you do not need 4-byte pointers to them to use amode31. About the only amode24 code for z/OS I write these days is for exits where only amode24 is supported. DCB exits pointed to by DCBEXLST may be in this boat, as are the SYSIN and SYSPRINT (and other DD ??) exits used for supplying data to and consuming data from calls to the IDCAMS program. Sometimes in rmode31 programs I GETMAIN BTL storage and load the code for DCB exits, but this technique is not required for EODAD and SYNAD exits due to their DCBE support. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
