OpenVMS Calling Standard

This document serves as a comprehensive technical reference for the OpenVMS calling standard, which provides the rules, conventions, and mechanisms for procedure-to-procedure communication in both VAX and Alpha environments. It defines run-time data structures, register usage, stack frame formats, and methods for parameter passing and function returns. Furthermore, the manual details the procedures for condition and exception handling, including how to establish handlers, signal conditions, and perform stack unwinding. The standard is intended primarily for systems programmers, compiler writers, and debugger implementers to ensure consistency and interoperability across languages and multithreaded environments on OpenVMS.