About z/XDC - Reviews - Sid Schipper:

This is what Sid Schipper,a senior programmer, has this to say about XDC:

I have been a software developer on IBM mainframe systems for almost 20 years. I have developed systems using just about every programming language you can think of, but my main area of expertise is IBM assembler language programming. I have been using Cole Software's XDC debugger for about three years now and have found it to be an extremely useful and informative tool. It is much easier to use than the TSO TEST command and is of course superior to using dumps. The cross domain facility (XDCCDF) is especially useful when debugging large systems that involve multiple address spaces.

If you need to do assembler language debugging I highly recommend Cole Software's XDC debugger.

Sid Schipper