TAL Programmer's Guide

Using Parameters
Using Procedures
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Procedure Parameter Area The system creates a private parameter area for each activation of a procedure. Before
control passes to the called procedure, the system stores any actual parameter values
in the private parameter area.
For each activation of a procedure, the parameter area provides storage for:
Up to 32 named parameters with no limit on the number of words of parameters.
(The compiler generates code for accessing parameter words beyond L-31.)
One of the following parameter masks, if present:
A one-word or doubleword VARIABLE parameter mask
A one-word to eight-word EXTENSIBLE parameter mask, plus a word value
that represents the number of parameter words passed, stored in its negative
form
Subprocedure
Parameter Area
The system creates a private parameter area for each activation of a subprocedure.
Before control passes to the called subprocedure, the system stores any actual
parameter values in the private parameter area.
For each activation of a subprocedure, the parameter area provides storage for up to 30
words of parameters, less storage required for sublocal variables and for a word or
doubleword parameter mask, if present.
Scope of Formal
Parameters
The scope of an identifier is its visibility in the program; that is, the part of the
program from which the identifier is accessible. Formal parameters have either:
Local scope if declared in a procedure
Sublocal scope if declared in a subprocedure
Normally, local statements can access global identifiers, and sublocal statements can
access local identifiers in the encompassing procedure and global identifiers.