On Mon, 13 Mar 2017 13:42:09 -0400, Tony Harminc <[email protected]> wrote:
>There's a good writeup in the z/OS UNIX Assembler Callable Services >book, under "Linkage conventions for the callable services" in Chapter >1. (The TCP/IP services are part of the more general UNIX services.) >There is no mention of any R13 requirement, and this makes sense >because all the callable services are stubs that figure out which PC >to issue, and then issue it. There isn't much that these stubs can do to figure out what PC to issue without using any registers. I looked for "save area" in that manual and found references in Appendices E and F that seem to indicate a requirement for a save area address in R13. The reference to the z/OS MVS Program Management:Advanced Facilities manual for detailed linkage information is confusing. It seems to me more likely that they meant the Assembler Programmer's Guide rather than a binder manual. >What is slightly less clear is if R15 >must point to the entry point of what you call. It seems clear to me. "Register 15 is set up by the CALL macro; it contains the entry point address of the service stub that is being called." In any case, R14 is the return address. That is standard linkage, not XPLINK. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
