Protecting procedures and programs from being interrupted
By setting the operand value INTERRUPT-ALLOWED=*NO in SET-PROCEDURE-OPTIONS or in MODIFY-PROCEDURE-OPTIONS, a procedure can be protected against interruptions by commands input in dialog mode.
If a program is activated in a procedure, the procedure must also be protected against uncontrolled command inputs; e.g. if the program is processing data or statements, and some of these request the program to execute commands (CMD macro) or to issue an interrupt (BKPT) which is not provided for in the procedure.
Example
/SET-PROCEDURE-OPTIONS ...,INTERRUPT-ALLOWED=NO
/ASSIGN-SYSDTA TO=*PRIMARY
/START-LMS
----------> Dialog at the terminal:
//
//...
//END
/MODIFY-JOB-SWITCHES ON=(4,5)
/START-EDT
----------> Dialog at the terminal:
*
* ...
*
/EXIT-PROC
If a procedure is protected against interruption, then normally any program which is executed in this procedure is also protected against interruption by the 
key. However, if a STXIT routine is defined in the program for interruptions (ESCPBRK), then the event is passed to this STXIT routine. Responsibility for handling this event then lies with the program. This will in any case lead to problems, if the program reacts with a BKPT macro.
Example
/SET-PROCEDURE-OPTIONS ...,INTERRUPT-ALLOWED=NO
/START-EXECUTABLE-PROGRAM ...
//
//... <--------------[K2]
[K2]-STXIT> Output PC
BKPT
“Return to the command level”
/EXIT-PROCEDURE