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TlsAlloc allocates a thread local storage (TLS) index. Any thread of the process can subsequently use this index to store and retrieve values that are local to the thread.
Syntax
DWORD TlsAlloc(VOID);
Parameters
This function has no parameters.
Return Values
A TLS index if the function succeeds, 0xFFFFFFFF if the function fails
To get extended error information, call GetLastError.
The threads of the process can use the TLS index in subsequent calls to TlsFree, TlsSetValue, or TlsGetValue.
TLS indexes are typically allocated during process or dynamic-link library (DLL) initialization. Once allocated, each thread of the process can use a TLS index to access its own TLS storage slot. To store a value in its slot, a thread specifies the index in a call to TlsSetValue. The thread specifies the same index in a subsequent call to TlsGetValue, to retrieve the stored value.
The constant TLS_MINIMUM_AVAILABLE defines the minimum number of TLS indexes available in each process. This minimum is guaranteed to be at least 64 for all systems.
TLS indexes are not valid across process boundaries. A DLL cannot assume that an index assigned in one process is valid in another process. A DLL might use TlsAlloc, TlsSetValue, TlsGetValue, and TlsFree as follows:
NOTE: Since DllMain is only called for RTDLLs at process attach (and not thread attach) it can only be used in an RTDLL to maintain per-process data for the initializing thread. It cannot be used in an RTDLL to maintain thread local storage for any additional threads.
Requirements
Library | Rtx_Rtss.lib |
See Also: