Ownership of Global Memory Allocated by a DLL

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows versions 3.1 and 3.0

SUMMARY

In the Microsoft Windows environment, when a function in a dynamic- link library (DLL) calls the GlobalAlloc function without specifying the GMEM_DDESHARE flag in the wFlags parameter, the returned global memory object belongs to the currently active instance of the application that called the DLL. If that instance of the application terminates, the memory is freed. If the DLL is unloaded before the application terminates, the memory remains allocated.

If the function specifies the GMEM_DDESHARE flag when calling the GlobalAlloc function, the DLL owns the returned memory object. The memory is freed when the DLL is unloaded, not when any application terminates.

This behavior will continue for 16-bit applications in all future versions of the Microsoft Windows graphical environment. However, applications written for Windows NT may be required to free GMEM_DDESHARE memory explicitly by calling the GlobalFree function. In other words, the system may not free GMEM_DDESHARE memory when either the DLL or the application terminates.