Handling of detectable self-modifying assembler code

When z/OS® Debugger identifies detectable, self-modifying code, it indicates the situation in the Source window by putting an "X" in the column immediately before the column indicating a macro-generated instruction. A breakpoint cannot be set on such an instruction nor will STEP stop on such an instruction.

The EQAMODIN macro in shipped in the z/OS Debugger sample library (hlq.SEQASAMP). This macro can be used to make non-detectable, self-modifying code detectable. It generates no executable code. Instead it simply adds information to the SYSADATA file to identify the specified operand as modified. The operand can be specified either as a label name or as "*" to indicate that the immediately following instruction is modified.