HLASM Language Reference

Introduction to Macro Language
Macro Library
The same macro definition may be made available to more than one source
program by placing the macro definition in the macro library. The macro library is a
collection of macro definitions that can be used by all the assembler language
programs in an installation. When a macro definition has been placed in the macro
library, it can be called by coding its corresponding macro instruction in a source
program. Macro definitions must be in a macro library with a member name that is
the same as the macro name. The procedure for placing macro definitions in the
macro library is described in the applicable utilities manual.
The DOS/VSE assembler requires library macro definitions to be placed in the
macro library in a special edited format. High Level Assembler does not require
this. Library macro definitions must be placed in the macro library in source
statement format. If you wish to use edited macros in VSE you can provide a
LIBRARY exit to read the edited macros and convert them into source statement
format. A library exit is supplied with VSE and is described in VSE/ESA Guide to
System Functions.
System Macro Instructions
The macro instructions that correspond to macro definitions prepared by IBM are
called system macro instructions. System macro instructions are described in the
applicable operating system manuals that describe macro instructions for supervisor
services and data management.
Conditional Assembly Language
The conditional assembly language is a programming language with most of the
features that characterize a programming language. For example, it provides:
Variables
Data attributes
Expression computation
Assignment instructions
Labels for branching
Branching instructions
Substring operators that select characters from a string
Use the conditional assembly language in a macro definition to receive input from a
calling macro instruction. You can produce output from the conditional assembly
language by using the MNOTE instruction.
Use the functions of the conditional assembly language to select statements for
generation, to determine their order of generation, and to do computations that
affect the content of the generated statements.
The conditional assembly language is described in Chapter 9, “How to Write
Conditional Assembly Instructions” on page 318.
242 HLASM V1R5 Language Reference