This article was previously published under Q126962
When you run a large number of Windows-based programs, "Out Of Memory"error messages appear when you attempt to start new programs or try to useprograms that are already running, even though you still have plenty ofphysical and pagefile memory available.
This behavior can occur if the desktop heap in the WIN32 subsystem isdepleted.
Note This problem occurs more often under Windows NT 3.5 as the default size of the desktop heap is 512K. Under Windows NT 3.1 the default value is 3072K. The default was reduced to increase performance.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
For Windows NT: SharedSection specifies the system and desktop heaps using the following format:
Add ",256" or ",512" after the yyyy number.
For Windows 2000, Windows XP, and Windows Server 2003: SharedSection uses the following format to specify the system and desktop heaps:
For 32-bit operating systems, increase the yyyy value to "12288"; Increase the zzzz value to "1024". For 64-bit operating systems, increase the yyyy value to "20480"; Increase the zzzz value to "1024".
Windows NT uses a special memory heap for all Windows-based programsrunning on the desktop. The desktop heap is used for all objects (windows,menus, pens, icons, etc.). When a large number of Windows-basedprograms are running, this heap may run out of memory. When there isnot enough memory to satisfy an allocation request, the system normallyreturns an error and notifies the user that they are running low onmemory. Some programs do not handle the failure gracefully, and in somecases there may not be enough memory to create the error message dialog box. As a result, the requested operation fails without any indication.
The SharedSection key is a long string when viewed using Registry Editor.The default value for this key is as follows.
The first SharedSection value (1024) defines the heap size common to alldesktops. This includes the global handle table (Window handles are uniquemachine wide) and shared system settings (such as SystemMetrics). It isunlikely you would ever need to change this value.
The second SharedSection value (3072) controls the size of the desktopheap that is associated with an interactive window station (used for Windows objects). This static value is used to prevent ill- behaved applications from consuming too many resources. Because the desktop heap is mapped into each process' address space, this value should not be set to an arbitrarily high value (as it would decrease performance), but should only be increased sufficiently to allow all the desired applications to run.
The third SharedSection value (512) controls the size of the desktop heap for each desktop that is associated with a "non-interactive" window station. If this value is not present, the size of the desktop heap for non-interactive window stations will be same as the size specified for interactive window stations (the second SharedSection value). For more information about the parameters of the SharedSection key, click the following article number to view the article in the Microsoft Knowledge Base:
184802 PRB: User32.dll or Kernel32.dll fails to initialize
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