On z/OS clients, the command is passed to the PGM executor. The first token of the command string is interpreted as a load module and the remainder as a PARM string. As an example, the following statement calls the load module IEBUPDTE, passing the PARM string “NEW”.
.SYSTEM “IEBUPDTE NEW”;
This command calls IEBUPDTE in the same way it is called via the JCL statement:
//EXEC PGM=IEBUPDTE,PARM='NEW'
On z/OS, the program must be present in the STEPLIB or JOBLIB concatenation, be resident in one of the LPAs, or be located in the linklist concatenation.
Otherwise, the invocation will fail, with code SYS_ABTM (-14) returned, resulting from an underlying abend S806-04. Other types of failures also are possible.
On UNIX OS clients, the SYSTEM command invokes the standard UNIX OS interface to issue the command to the shell (sh), and waits for its completion.