libst1 1.9-3.1ubuntu1 (amd64 binary) in ubuntu zesty

 The State Threads library has an interface similar to POSIX threads.
 .
 However, the threads are actually all run in-process. This type of
 threading allows for controlled schedualing points. It is highly useful
 for designing robust and extremely scalable internet applications since
 there is no resource contention and locking is generally unnecessary.
 .
 It can be combined with traditional threading or multiple process
 parallelism to take advantage of multiple processors.
 .
 This package provides the library required by dependent programs.