3. Interactive execute and debug

To execute a RXS program, write the program in any dataset on the mainframe using ISPF edit, write rxs in the command line in the edit screen (==> rxs) and press the enter key. No allocation of the dataset containing the program is necessary. It is not necessary to 'save' the program before execution: the RXS interpreter works as an ISPF-macro. The dataset may have COBOL numbers, these are ignored in the interpretation of the program, but output will be generated using COBOL numbers in this situation.

In case of errors, error messages from RXS will pop up over the line in error in the program.

ISPF command ==> hilite rexx will syntax color what is on the screen, and that can be very handy, especially because quotes are used quite intensive in RXS. This syntax colouring highlights unbalanced quotes.

RXS programs also may be executed as TSO commands. The prerequisite is that these RXS programs are members in a dataset allocated to the TSO session as file RXSLIB (Section 35).

RXS programs may also be executed from JCL (Section 36).

RXS programs must execute inside TSO + ISPF environment.

Debugging

When debugging is needed, note the following:

• The RXS command say xxx is excellent for debugging. The command writes strings and variables on the screen during execution.
• Error messages from RXS always contains a header: "RXS error:", "REXX error:", "SQL error:" and so on. If some coding conflicts with REXX syntax rules, a REXX manual can be useful. Etc.
• RXS encourages incremental programming: Write a couple of action blocks and execute. Build on when successful.
• Marking a block of lines with line commands 'cc' 'cc' will direct RXS to execute the marked block only

To halt a RXS program

If execution of a RXS program has to be stopped, press the 'Esc' button, which starts a termination dialogue. Now enter hi for 'halt immediate'.