ARCHIVED: What are the GDI heap and the USER heap?

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The GDI (graphical device interface) heap is one of the systemwide resources in the Windows environment. Its counterpart is the USER heap. Each is limited to 64KB and is shared by all the applications.

When you launch an application in Windows, an object is placed in the USER heap. Most applications also place a GDI object in the GDI heap. If the USER heap or the GDI heap become full, your computer can crash.

Theoretically, memory is reclaimed from the USER heap when you exit an application. However, this does not always occur.

When you exhaust your GDI and USER heaps, you might see the outline of icons, or a partially drawn window. Perhaps some of the graphics will look like black boxes. The number of windows you can open simultaneously is also limited to the available space in the USER heap.