@Aladdin Of course, there are many other ways to describe the same region, I went for z first - since that seems to be the simpler. (It has rotational symmetry around z-axis.)
I am not really sure what you mean by "outer limit is z". In any case, I checked the range for z and checked what happened for a fixed z.
I assumed you want to find bound for integration - similarly as in your previous questions.
If you're trying to do something else, you should explain what actually is the question.
If anyone is around I am doing some practice problems for an introductory real analysis class that I am in and am stuck on one problem in particular that is driving me nuts, and I would really appreciate the help.