>>-MSTep-------------------------------------------------------><

The MSTEP command is different to STEP because the target program is executed before control returns to the issuing macro. When STEP is issued from a macro, it has no immediate effect, being processed after the macro exits.

After issuing MSTEP, the macro can use EXTRACT EVENT to determine what kind of event occurred in the target program. In general this indicates that a STEP has occurred, but it may also indicate some other condition (for example, a program check).

z/VM

You should ensure that the MSTEP command is issued through the LPSW Fastpath addressing environment, which is the default environment established when the IDF macro is entered. Using this interface eliminates any SVC linkages between REXX and IDF, so that IDF can provide optimum flexibility in what the target program can itself execute under MSTEP. See the usage notes under MRUN for further details.

1. If you have subroutines within the program which you do not want to single-step through, use the SKIPSTEP command. The SKIPSTEP command causes IDF to skip single stepping when it comes to a subroutine call to a subroutine that was added to the list of subroutines being skipped. For the purposes of single-stepping, the skipped subroutine is treated as one instruction, the subroutine call instruction itself. If a breakpoint or a watchpoint whose condition is true is placed within the execution path of the subroutine being skipped, execution stops at that breakpoint or watchpoint.
2. If the STOPNOP option is OFF or the NOSTOPNP option is ON, then IDF does not stop on NOP and NOPR instructions that follow BAL, BALR, BAS, and BASR instructions.

Return codes

0

Operation successful

6

The target program is not yet loaded