Managing memory and its problems was an important part of running Classic Mac OS, but everything changed in Mac OS X. Do we still need apps to do that?
Mach zone
How to tell whether an app has a memory leak, what to do about it, and the differences from a kernel memory leak.
What’s the difference between an app and kernel memory leak? How would you notice one, and how to investigate it, and (sometimes) work around the problem.
When a kernel extension wants some memory, it calls for an allocation from a Mach zone. This explains how a memory leak in those zones can result in a kernel panic.
The Eclectic Light Company 