SAP Open Server uses POSIX threads.
When you use threaded libraries (*_r), link with the pthreads library.
See the Open Client and Open Server Programmers Supplement for UNIX for information on Open Client libraries.
The thread-safe version of Open Client libraries are written using POSIX threads. All multithreaded libraries use the naming pattern *_r.a for static libraries or *_r.so for shared libraries. For multithreaded applications, use libraries with the “_r” suffix, such as libcs_r.a. For non-multithreaded applications, use libraries without the “_r” suffix, such as libcs.a.