This variable is accessible from a debugger or your program and allows you to tune allocation diagnostics.
afxMemDF can have the following values as specified by the enumeration afxMemDF:
allocMemDF Turns on debugging allocator (default setting in Debug library).
delayFreeMemDF Delays freeing memory. While your program frees a memory block, the allocator does not return that memory to the underlying operating system. This will place maximum memory stress on your program.
checkAlwaysMemDF Calls AfxCheckMemory every time memory is allocated or freed. This will significantly slow memory allocations and deallocations.