InitializeCriticalSection function (synchapi.h)

Initializes a critical section object.


void InitializeCriticalSection(
  [out] LPCRITICAL_SECTION lpCriticalSection


[out] lpCriticalSection

A pointer to the critical section object.

Return value

This function does not return a value.

Windows Server 2003 and Windows XP: In low memory situations, InitializeCriticalSection can raise a STATUS_NO_MEMORY exception. Starting with Windows Vista, this exception was eliminated and InitializeCriticalSection always succeeds, even in low memory situations.


The threads of a single process can use a critical section object for mutual-exclusion synchronization. There is no guarantee about the order in which threads will obtain ownership of the critical section, however, the system will be fair to all threads.

The process is responsible for allocating the memory used by a critical section object, which it can do by declaring a variable of type CRITICAL_SECTION. Before using a critical section, some thread of the process must initialize the object.

After a critical section object has been initialized, the threads of the process can specify the object in the EnterCriticalSection, TryEnterCriticalSection, or LeaveCriticalSection function to provide mutually exclusive access to a shared resource. For similar synchronization between the threads of different processes, use a mutex object.

A critical section object cannot be moved or copied. The process must also not modify the object, but must treat it as logically opaque. Use only the critical section functions to manage critical section objects. When you have finished using the critical section, call the DeleteCriticalSection function.

A critical section object must be deleted before it can be reinitialized. Initializing a critical section that has already been initialized results in undefined behavior.


Requirement Value
Minimum supported client Windows XP [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 [desktop apps | UWP apps]
Target Platform Windows
Header synchapi.h (include Windows.h on Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008 Windows Server 2008 R2)
Library Kernel32.lib
DLL Kernel32.dll

See also


Critical Section Objects





Synchronization Functions


Vertdll APIs available in VBS enclaves