Developing and Porting C and C++ Applications on AIX

8.5. Thread-specific data

POSIX provides a mechanism that enables applications to maintain specified data on a per-Pthread basis. The mechanism is motivated by the need of some modules (that is, groups of related functions) to maintain selected data across function invocations (that is, to maintain static data in the C programming language). If such a module is being used by multiple Pthreads of a multi-threaded process, then the module may need to maintain such data separately for each calling Pthread, depending on the particular application.

Note

If a Pthread executes only one function during its life-cycle, it less likely needs thread-specific data. Because each Pthread has its own thread stack, all auto storage class variables in that function ...