Systems, methods, and computer products that determine how to optimize serialization code that has been ported from other computer systems to the OS/390 UNIX system. General-purpose UNIX systems may not provide sufficient facilities; such as compiler run-time APIs like the Compare and Swap C Run-Time Library API, to accommodate the performance-related features of serialized code in complex applications. When porting a high-performance application from other UNIX platforms to IBM OS/390 UNIX, serialized code performance of the application may be limited. The present invention may be implemented by advantageously determining when substitution of the Compare and Swap C Run-Time Library API calls for pthread_mutex calls will improve the execution of serialized code on the IBM OS/390 UNIX system.