HLASM Language Reference

Levels of Macro Call Nesting
Recursion
You can also call a macro definition recursively; that is, you can write macro
instructions inside macro definitions that are calls to the containing definition. This
is how you define macros to process recursive functions.
General Rules and Restrictions
Macro instruction statements can be written inside macro definitions. Values are
substituted in the same way as they are for the model statements of the containing
macro definition. The assembler processes the called macro definition, passing to
it the operand values (after substitution) from the inner macro instruction. In
addition to the operand values described in “Values in Operands” on page 307,
nested macro calls can specify values that include:
Any of the symbolic parameters (see ▌1▐ in Figure 84) specified in the
prototype statement of the containing macro definition
Any SET symbols (see ▌2▐ in Figure 84) declared in the containing macro
definition
Any of the system variable symbols such as &SYSDATE, &SYSTIME, etc.
(see ▌3▐ in Figure 84).
┌──────────── Parameters
│
MACRO ┌────────┴────────┐
OUTERMAC &P1,&P2,&KEY1=VALUE Prototype
. │
. ▌1▐
. │
LCLC &C──────────────►▌2▐
. │ │
. │ │
&C SETC 'ABC' │ │
. │ │
. ▼ ▼
INNERMAC &P1,&KEY1,&C Inner macro call
. └─────┬────┘
. └─────────────── Operands
.
MEND
─────────────────────────────────────────────────────────────────────
MACRO
OUT
Prototype
.
.
. ▌3▐ ▌3▐ ▌3▐
IN &SYSLIST(3),&SYSECT,A&SYSDNX Inner macro call
.
.
MEND
Figure 84. Values in Nested Macro Calls
The number of nesting levels permitted depends on the complexity and size of the
macros at the different levels; that is, the number of operands specified, the
number of local-scope and global-scope SET symbols declared, and the number of
sequence symbols used.
Chapter 8. How to Write Macro Instructions 313