The system enforces the following rules when you use system symbols
in system commands. They apply
in addition to
the general rules for system symbols that are described in
z/OS MVS Initialization and Tuning Reference.
- Substitution in a command begins after the command name. This
means that you cannot use symbolic variables to resolve to a command
prefix or to a command name. The command “&Asyspref &mycmd”
would result in an error message, for example.
- If the issuing console has command association (CMDSYS) to another
system, the issuing system first transports the command to the associated
system. Substitution of any symbolic variables takes place on the
receiving system.
- If a command has a prefix defined with the command prefix facility
(CPF), the issuing system first transports the command to the system
defined for that prefix. Substitution of any symbolic variables takes
place on the receiving system.
- After echoing and logging a command, the system examines the command
name. Certain commands receive special treatment:
- The system will not perform substitution for symbolics in a VARY
CN(*),ACTIVATE command.
- A DUMPDS command will not undergo substitution. The DUMPDS command
processor handles its own substitutions, at the time when it actually
takes a dump.
- For security reasons, the LOGON command does not support symbolic
substitution.
- For a REPLY command, substitution of any symbolic variables in
the reply text takes place on the system originally issuing the WTOR.
However,
if the WTOR is synchronous (SYNCH = YES was specified, and the synchronous
WTO/R service displays the WTOR), the system does not perform substitution
of the reply text.
But, if the system issues the WTOR early
during the initial program load (IPL), that is, while the nucleus
initialization program (NIP) is still in use:
- The system performs substitution after it processes the requested
symbolics it reads from the parmlib. This means that the system will substitute symbolic variables in replies
to WTORs it issues after issuing the IEA347A
SPECIFY MASTER CATALOG PARAMETER message.
- The system will not issue message IEE295I for NIP-time replies
that are changed by symbolic substitution. Message IEE600I will reflect
the changed text.
- For a ROUTE command, the system issuing the command performs the
substitutions up through the specification of the destination system(s).
Each destination system completes the substitution of the text for
the command.
For example, if you code the command
RO T=&T1,&SYSGRP1,F JOB&SYSCLONE,parms
the
system issuing that ROUTE command will substitute the variables
&T1 and &SYSGRP1
and
each system in the system group that &SYSGRP1 names will issue
the command
F JOB&SYSCLONE,parms
and each of those
receiving systems will substitute its own value for &SYSCLONE.
See “Using System Symbols in ROUTE Commands.”
- You cannot use symbolic variables on an “L=” operand to
aggregate the command response when sending a command to more than
one system. The system will not substitute for the “L=” operand.
- For commands other than REPLY and ROUTE, the system issuing the
command performs the substitution for the text after the command name,
including comments.
- You cannot use system symbols in commands that control batch jobs.
Consider converting batch jobs to started tasks, which can specify system symbols.
- If substitution results in changing any command text, the system
logs the “new” text again and issues message IEE295I.
The
system makes the original (pre-substitution) command text available
to the command installation exits and the subsystem interface (SSI).
However, current programs, if not modified, will see the substituted
text.
When the system calls the command installation exits
or SSI, if those exits make any change to the command text, the system
logs them again and issues message IEE295I. However, it does not
perform substitution again. It frees the original command text, which
means that it is no longer available in the system.