The WM_COMPACTING message is sent to all top-level windows when the system detects more than 12.5 percent of system time over a 30- to 60-second interval is being spent compacting memory. This indicates that system memory is low.
A window receives this message through its WindowProc function.
Note This message is provided only for compatibility with 16-bit Microsoft Windows-based applications.
Syntax
WM_COMPACTING
WPARAM wParam
LPARAM lParam;
Parameters
- wParam
-
Specifies the ratio of central processing unit (CPU) time currently spent by the system compacting memory to CPU time currently spent by the system performing other operations. For example, 0x8000 represents 50 percent of CPU time spent compacting memory.
- lParam
-
This parameter is not used.
Return Value
If an application processes this message, it should return zero.
Remarks
When an application receives this message, it should free as much memory as possible, taking into account the current level of activity of the application and the total number of applications running on the system.
Notification Requirements
| Minimum DLL Version |
None |
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| Header | Declared in Winuser.h, include Windows.h |
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| Minimum operating systems |
Windows 95, Windows NT 3.1 |
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See Also
Windows Overview