On Solaris, the Solaris native and POSIX 1003.1c thread APIs are supported. While the POSIX API simply wraps the underlying Solaris thread library, it does not provide access to the same capabilities as is available from the native library. When possible, you should configure the Threads Module to use the native library as this will give you the greatest level of control over your threads. According to Sun, you can mix these APIs within a single application, but this requires a complicated build process, and is not recommended.