Updated: 11 December 1998

Guide to Creating OpenVMS Modular Procedures

• A procedure should not allocate static storage unless it is a processwide, resource-allocating procedure, or unless it must retain results for implicit inputs on subsequent invocations.
• Timing procedures and resource allocation procedures should make statistics available for performance evaluation and debugging by providing the entry points fac_SHOW_name and fac_STAT_name. (Optional. See Section 4.3.)
• If a procedure uses a processwide resource, it calls the appropriate resource allocating library procedure or system service to allocate the resource to avoid conflict with allocations made to other procedures. To conserve resources, a procedure that requests resource allocation does one of the following:
  • Calls the deallocation procedure before returning to the calling program
  • Remembers the allocation in static storage and calls the deallocation procedure later
  • Passes the responsibility for deallocation back to the calling program
  • Allocates a fixed number of the resources, independent of the number of times it is called (See Section 2.4 and Section 3.1.3.)

• Each module must be documented with a module description. (See Section 2.5.1.)
• Each procedure must be documented with a procedure description. (See Section 2.5.2.)
• When symbol definitions are to be coordinated between more than one module (such as control blocks, procedure argument values, and completion status codes), the definitions should be centralized in a common source file. Note, however, that the modules must be written in the same language. (See Section 3.1.2.)
• Procedure entry point names, module names, and PSECT names must conform to the naming conventions. (See Section 3.1.1.2, Section 3.1.1.4, and Section 3.1.1.5.)
• Digital recommends that you also adhere to the naming conventions in choosing names for facilities and files. (Optional. See Section 3.1.1.1 and Section 3.1.1.3.)

When a new version of a procedure replaces an existing library procedure, all new arguments should be added at the end of the call sequence and made optional to maintain upward compatibility. (Optional. See Section 2.2.5 and Chapter 6.)

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