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Contains information about the current state of both physical and virtual memory. The GlobalMemoryStatus function stores information in a MEMORYSTATUS structure.


typedef struct _MEMORYSTATUS {
  DWORD  dwLength;
  DWORD  dwMemoryLoad;
  SIZE_T dwTotalPhys;
  SIZE_T dwAvailPhys;
  SIZE_T dwTotalPageFile;
  SIZE_T dwAvailPageFile;
  SIZE_T dwTotalVirtual;
  SIZE_T dwAvailVirtual;



The size of the MEMORYSTATUS data structure, in bytes. You do not need to set this member before calling the GlobalMemoryStatus function; the function sets it.


A number between 0 and 100 that specifies the approximate percentage of physical memory that is in use (0 indicates no memory use and 100 indicates full memory use).


The amount of actual physical memory, in bytes.


The amount of physical memory currently available, in bytes. This is the amount of physical memory that can be immediately reused without having to write its contents to disk first. It is the sum of the size of the standby, free, and zero lists.


The current size of the committed memory limit, in bytes. This is physical memory plus the size of the page file, minus a small overhead.


The maximum amount of memory the current process can commit, in bytes. This value should be smaller than the system-wide available commit. To calculate this value, call GetPerformanceInfo and subtract the value of CommitTotal from CommitLimit.


The size of the user-mode portion of the virtual address space of the calling process, in bytes. This value depends on the type of process, the type of processor, and the configuration of the operating system. For example, this value is approximately 2 GB for most 32-bit processes on an x86 processor and approximately 3 GB for 32-bit processes that are large address aware running on a system with 4 GT RAM Tuning enabled.


The amount of unreserved and uncommitted memory currently in the user-mode portion of the virtual address space of the calling process, in bytes.


MEMORYSTATUS reflects the state of memory at the time of the call. It also reflects the size of the paging file at that time. The operating system can enlarge the paging file up to the maximum size set by the administrator.

On computers with more than 4 GB of memory, the MEMORYSTATUS structure can return incorrect information, reporting a value of –1 to indicate an overflow. If your application is at risk for this behavior, use the GlobalMemoryStatusEx function instead of the GlobalMemoryStatus function.


For an example, see the GlobalMemoryStatus function.


Minimum supported client

Windows XP [desktop apps only]

Minimum supported server

Windows Server 2003 [desktop apps only]


WinBase.h (include Windows.h)

See also

Memory Performance Information



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