When a process is started, a small block of memory is set aside to be used as a thread-local memory area. This memory is at the same virtual address for each thread, but is backed by different physical memory. This permits each thread to have a small block of memory that is unique, or local, to that thread.

The thread-local memory area consists of 32 DWORDs (128 bytes), each DWORD being 32-bits in size.