Limitations when debugging on TSO

The following limitations apply on TSO:

IDF can only be used to debug programs that have their own (E)SPIE or (E)STAE exits if SVC 97 is used for breakpoints. The default is to use SVC 97 for breakpoints. You can override this by using the NOSVC97 option, or a SET OPTION ON NOSVC97 command in the PROFILE macro. For more details see Breakpoint method selection (TSO).
IDF cannot debug programs that issue ISPF SELECT service calls or those that involve z/OS multitasking unless SVC 97 is used for breakpoints. The default and override are as for the previous point.
The REXX system interface requires that external functions return an EVALBLOK. If you are debugging a REXX function package that has been called by a REXX exec and you quit from IDF before the function has completed, the REXX interpreter issues an error message. You may need to logoff TSO and log back on.