XL C provides two sets of functions for debugging memory problems:
Both sets of debugging functions have their benefits and drawbacks. The one you choose to use depends on your program, your problems, and your preference.
The heap-checking functions perform more general checks on the heap at specific points in your program. You have greater control over where the checks occur. The heap-checking functions also provide compatibility with other compilers that offer these functions. You only have to rebuild the modules that contain the heap-checking calls. However, you have to change your source code to include these calls, which you will probably want to remove in your final code. Also, the heap-checking functions only tell you if the heap is consistent or not; they do not provide the details that the debug memory management functions do.
On the other hand, the debug memory management functions provide detailed information about all allocation requests you make with them in your program. You don't need to change any code to use the debug versions; you need only specify the -qheapdebug option.
A recommended approach is to add calls to heap-checking functions in places you suspect possible memory problems. If the heap turns out to be corrupted, you can rebuild with -qheapdebug.
Regardless of which debugging functions you choose, your program requires additional memory to maintain internal information for these functions. If you are using fixed-size heaps, you might have to increase the heap size in order to use the debugging functions.