TlsSetValue

This function stores a value in the calling thread's thread local storage (TLS) slot for a specified TLS index. Each thread of a process has its own slot for each TLS index.

At a Glance

Header file:	Winbase.h
Windows CE versions:	1.0 and later

Syntax

BOOL TlsSetValue( DWORD dwTlsIndex, LPVOID lpTlsValue );

Parameters

dwTlsIndex

[in] Specifies a TLS index that was allocated by the TlsAlloc function.

lpTlsValue

[in] Pointer to the value to be stored in the calling thread’s TLS slot specified by dwTlsIndex.

Return Values

Nonzero indicates success. Zero indicates failure. To get extended error information, call GetLastError.

Remarks

TLS indexes are typically allocated by the TlsAlloc function during process or DLL initialization. Once allocated, each thread of the process can use a TLS index to access its own TLS storage slot for that index. The storage slot for each thread is initialized to NULL. A thread specifies a TLS index in a call to TlsSetValue to store a value in its slot. The thread specifies the same index in a subsequent call to TlsGetValue to retrieve the stored value.

TlsSetValue and TlsGetValue were implemented with speed as the primary goal. These functions perform minimal parameter validation and error checking. In particular, this function succeeds if dwTlsIndex is in the range 0 through (TLS_MINIMUM_AVAILABLE – 1). It is up to the programmer to ensure that the index is valid.