Enter the IRXJCL parameter in the free-form text field labeled: Other options. For more information about IRXJCL and the format of the parameter see the TSO/E REXX Reference manual.
Typically this is where you would specify the REXX exec to invoke and the arguments for that exec. For example, the following free-form text specifies that the "BLD$LOGS" exec be invoked with arguments "MBR(DFSIC460) DIR(/tmp)" and option "LOG(2)":
BLD$LOGS MBR(DFSIC460) DIR(/tmp) ( LOG(2)
The following breaks down the free_form text into its components for clarity:
BLD$LOGS
MBR(DFSIC460) DIR(/tmp)