# Using high performance libraries

IBM z/OS® XL C/C++ is shipped with a set of libraries
for high-performance mathematical computing:

- The Mathematical Acceleration Subsystem (MASS) is a set of libraries of tuned mathematical intrinsic functions that provide improved performance over the corresponding standard system math library functions. MASS is described in Using the Mathematical Acceleration Subsystem (MASS) libraries.
- The Automatically Tuned Linear Algebra Software (ATLAS) is a set of high-performance, processor-tuned linear algebra libraries. ATLAS is described in Using the Automatically Tuned Linear Algebra Software (ATLAS) libraries.