You can use any of the instructions you listed while in AMODE 31. They should be no faster or slower in either AMODE 31 or 64. The only reason you need AMODE 64, from your description, is to use storage above the bar. This will mean using a z/OS service to request the allocation of the storage. The execution time of IARV64, for example, could be slower than perhaps STORAGE OBTAIN which you might have been using previously, but beyond that the execution of your program's code should not be slower just because of the AMODE.
I wrote a blog post about programming for RMODE 64 back in October 2014. It is mostly about RMODE 64 code but also contains some hints about writing AMODE 64 code you might find useful. You can find the post on our website at http://zosdebug.com/blog. Chuck Arney Arney Computer Systems Web: http://zosdebug.com Facebook: http://www.facebook.com/arneycomputer -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Brite Sent: Tuesday, May 05, 2015 8:36 AM To: [email protected] Subject: Re: LNKEDT 64-bit mode assembler in AMODE 31 I compared to the performance of same programs before they were converted to 64-bit. How do those 64-bit instructions (e.g. LGR, STMG, LMG) work in 31-bit AMODE? This is the first I have to deal with 64-bit mode.
