OpenVMS Calling Standard

The OpenVMS Calling Standard defines the run-time requirements for procedure-to-procedure interaction across OpenVMS Alpha and VAX environments. It provides essential specifications for compiler, debugger, and system tool developers. Key topics include:

• Conventions: Detailed register usage, stack frame formats, and calling sequences for both VAX and Alpha architectures.
• Data Passing: Standards for argument-passing mechanisms (immediate value, reference, descriptor) and the structure of argument lists.
• Argument Descriptors: Technical definitions for self-describing argument descriptors used across 32-bit and 64-bit environments.
• Exception Handling: Defines the OpenVMS condition-handling framework, including signal vectors, condition values, and unwinding procedures.
• Interoperability: Specifies requirements for native-to-translated code interoperation in the OpenVMS Alpha environment.