Multithreading support v15
OCL is supported in a multithreaded environment. You can enable and use multithreading in a multithreaded environment by making an OCIEnvNlsCreate() call with OCI_THREADED as the value of the mode parameter.
retCode = OCIEnvNlsCreate( &envp, OCI_THREADED, NULL, NULL, NULL, NULL, 0, NULL, 0, 0 );
All subsequent calls to OCIEnvNlsCreate() must also be made with OCI_THREADED.
OCI library manages mutexes for the application for each environment handle if a multithreaded application is running on a thread-safe operating system.