Why Static variable initialization internally tries to acquire _lock(_EXIT_LOCK1)

Question

Why Static variable initialization internally tries to acquire _lock(_EXIT_LOCK1)?

Here is the calls stack when the initialization of a local static variable happens.

*MSVCR80!_lock+0x2e

MyDLL32.dll!_onexit(int (void)* func=0x0864ae10) Line 103 C

MyDLL32.dll!atexit(void (void)* func=0x0864ae10) Line 127 + 0x9 bytes C*

Can you please explain why tries to acquire _lock(_EXIT_LOCK1)? C:\Program Files\Microsoft Visual Studio 8\VC\crt\src\atonexit.c _lock(_EXIT_LOCK1); // Line 103