Using the services

Macros and callable services are programming interfaces that application programs can use to access MVS™ system services. This chapter provides general information and guidelines about how to use the macros and callable services accurately and efficiently. For more specific and detailed information about coding a particular macro or callable service, see the individual service description in this information.

Some of the topics covered in this chapter apply only to macros, some apply only to callable services, and some apply to both. This chapter uses the word "services" when referring to information that applies to both service types. When information applies only to one type or the other, the particular service type is specified.

Note: z/OS® macros do not code to restrictions that are imposed by the COMPAT(CASE) HLASM option or its abbreviation CPAT(CASE). Therefore, you cannot rely on using COMPAT(CASE) if you use z/OS macros.

The following table lists the topics covered in this chapter and whether the topic applies to macros, callable services, or both:

Topic	Service Type
Compatibility of MVS macros	Macros
Addressing mode (AMODE)	Both
Address space control (ASC) mode	Both
ALET qualification	Both
User parameters	Macros
Telling the system about the execution environment	Macros
Specifying a macro version number	Macros
Register use	Both
Handling return codes and reason codes	Both
Handling program errors	Both
Handling environmental and system errors	Both
Using X-macros	Macros
Macro forms	Macros
Coding the macros	Macros
Coding the callable services	Callable Services
Including equate (EQU) statements	Callable Services
Link-editing linkage-assist routines	Callable Services
Service summary	Both