I don't know if this is the case here, but it is possible to write a program to run in addressing mode 64 but use 32 bit instructions so it works inside the 4GB address range.
On Fri, Nov 1, 2024 at 11:46 AM Tony Harminc <t...@harminc.net> wrote: > > On Fri, 1 Nov 2024 at 08:59, René Jansen <rvjan...@xs4all.nl> wrote: > > > Reading through the release notes (the "what's new") of the LLVM-Clang > > based C/C++ compiler for z/OS I see support for 32-bit programs and > > XPLINK32 linkage. Now I have to admit that I not followed all news closely > > but I even have a hard time googling this. I thought there is 24-,31- and > > 64-bit support on z/OS. Is this new and where can we read about this? > > > > I don't think there's anything architecturally new here - "32-bit" is often > used in the non-mainframe world as a contrast to "64-bit", and indeed even > S/360 can be said to be a 32-bit architecture. It's only the way that > address arithmetic and use works that uses 1 (21-bit) or 8 (24-bit) high > address bits as flags. In 64-bit mode all bits are address bits, i.e. there > is no 63-bit mode. > > More succinctly, it's "how wide are the registers", and perhaps "how big is > a pointer in C"? > > Tony H. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
