When the interpreter starts the interpretation of a Rexx procedure it checks the setting of the special environment variable, RXTRACE. If RXTRACE has been set to ON (not case-sensitive), the interpreter starts in interactive debug mode as if the Rexx instruction TRACE '?R' had been the first interpretable instruction. All other settings of RXTRACE are ignored. RXTRACE is only checked when starting a new Rexx procedure.

Use the SET command to set or query an environment variable or query all environment variables. To delete an environment variable, use SET variable=.