ID Number: Q21581
2.00 3.00
WINDOWS
Summary:
When an application calls LocalAlloc() and there is not enough memory
within the application's data segment, Windows will use memory from
the global heap to append this to the application's data segment.
Releasing the memory that was temporarily requested then becomes an
issue to the programmer.
For example, an initial HEAPWALK shows 12000 bytes free. After a 4K
LocalAlloc() and LocalLock(), HEAPWALK shows 4000 bytes locked and
8000 free. Then the program allocates and locks another 10K piece;
HEAPWALK shows 4000 bytes locked, 8000 free, and 10000 locked. If the
program then deallocates the 4K and 10K blocks with unlock and free,
HEAPWALK shows a free 12000 bytes and a free 10000 bytes. The
programmer then has the problem of releasing the second free 10K
block.
Using the LocalShrink() function will compact and shrink the data
segment to the smallest size possible. LocalShrink() cannot move FIXED
or locked blocks when compacting the local heap. Therefore, there may
still be free space in the heap, and the size of the heap may not be
as small as requested after calling LocalShrink(). However, this
function will compact as much as possible, given this constraint.