HLASM Language Reference

System Variable Symbols
System Variable Symbols
System variable symbols are a special class of variable symbols, starting with the
characters &SYS. Their values are set by the assembler according to specific rules.
You cannot declare them in local-scope SET symbols or global-scope SET
symbols, nor use them as symbolic parameters in macro prototype statements.
You can use these symbols as points of substitution in model statements and
conditional assembly instructions.
All system variable symbols are subject to the same rules of concatenation and
substitution as other variable symbols.
A description of each system variable symbols begins on page 263.
You should not prefix your SET symbols with the character sequence &SYS.
The assembler uses this sequence as a prefix to all system variable symbol
names, and using them for other SET symbol names might cause future
conflicts.
Scope and Variability of System Variable Symbols
Global Scope: Some system variable symbols have values that are established at
the beginning of an assembly and are available both in open code and from within
macros. These symbols have global scope. Most system variable symbols with
global scope have fixed values, although there are some whose value can change
within a single macro expansion. The global-scope system variables symbols with
variable values are &SYSSTMT, &SYSM_HSEV, and &SYSM_SEV.
Local Scope: Some system variable symbols have values that are available only
from within a macro expansion. These system variables have local scope. Since
the value of system variable symbols with local scope is established at the
beginning of a macro expansion and remains unchanged throughout the expansion,
they are designated as having constant values, even though they might have
different values in a later expansion of the same macro, or within inner macros.
Over half of the system variable symbols have local scope and therefore are not
available in open code.
262 HLASM V1R5 Language Reference