HeapAlloc with error: The data area passed to a system call is too small.

**wow** · 03-18-2006

Hi there,

What's the problem with the code below? It results in the error after calling HeapAlloc(hDictMem, HEAP_ZERO_MEMORY, 0x80000L):

The data area passed to a system call is too small.

But if 0x80000L is changed to 0x7e000L, then it works.

Code:

		// allocate memory for input method dictionaries
	hDictMem = (HANDLE) HeapCreate(HEAP_NO_SERIALIZE, 0x80016L, 0x80016L);
	if (NULL == hDictMem)
	{
		ErrorHandler();
		return (FALSE);
	}
	pDictMem = (LPSTR) HeapAlloc(hDictMem, HEAP_ZERO_MEMORY, 0x80000L);
	if (NULL == pDictMem)
	{
		ErrorHandler();
		return (FALSE);
	}

Thanks,

**anonytmouse** · 03-18-2006

Originally Posted by MSDN HeapCreate

However, the heap cannot grow, so the maximum size of a memory block in the heap is a bit less than 0x7FFF8 bytes. Requests to allocate larger blocks will fail, even if the maximum size of the heap is large enough to contain the block.

If dwMaximumSize is zero, the heap is growable. The heap's size is limited only by available memory. Requests to allocate blocks larger than 0x7FFF8 bytes do not automatically fail; the system calls the VirtualAlloc function to obtain the memory needed for such large blocks. Applications that need to allocate large memory blocks should set dwMaximumSize to zero.

Typically, when using HeapAlloc, one uses the process heap, obtainable with GetProcessHeap.

**wow** · 03-19-2006

Thanks very much, it works

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