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  Arguments
 
    pointer_variable    Pointer of any type, pointing to memory
                        previously allocated on heap
 
    size                Number of bytes to be deallocated
 
  Description
 
    The FreeMem procedure deallocates memory of a specified size,
    returning it to the heap. An assignment statement or call to the
    GetMem procedure must have previously set the pointer_variable
    argument to a location in the heap.
 
    The pointer can be of any type.
 
    The size argument specifies the size in bytes of the area to be
    deallocated.
 
    After the call to FreeMem, the pointer is undefined. The variable
    that the pointer pointed to is no longer valid. FreeMem does not
    affect other heap memory.
 
    FreeMem is similar to the Dispose procedure, which deallocates a
    dynamic variable of a specified type. Use FreeMem to free memory
    allocated by GetMem. Use Dispose to free a variable allocated
    by New.
 
    QuickPascal uses a free list to manage areas returned to the heap
    by Dispose and FreeMem. The free list is a list of pointers that
    grows downward (toward 0) from the top of the heap segment.
    FreePtr, defined in the System unit, points to the free list.
    Deallocated areas below the current top of the heap are pointed to
    by pointers kept in the free list. GetMem and New allocate from the
    free list before taking any new memory from the heap.
 
    Use caution when mixing methods for deallocating variables. Dynamic
    allocation and deallocation are usually done with the related pairs
    of procedures New/Dispose and GetMem/FreeMem. The Mark and Release
    procedures allow freeing of large areas of the heap at one time.
    Release clears the entire free list when called.
 
    If the size passed to FreeMem does not match the size of the
    variable intended for deallocation, memory errors can occur.
 
    If pointer_variable does not point to a memory location in the
    heap, the HeapError function provided at start-up causes a run-time
    error. It is possible to replace the default HeapError function
    with a custom function.