S/SL (pronounced "ess-sl") is a programming language designed for systems programming. It was developed by David Gries and Richard Hoare at IBM Research in the 1970s.
S/SL is based on the programming language PL/I. However, it is not a subset of PL/I; rather, it is a superset. S/SL adds features that are not present in PL/I, such as dynamic storage allocation, recursion, and exception handling.
S/SL is a compiled language. It is typically used on IBM mainframe systems.
S/SL has been used in a number of commercial applications, including the IBM DB2 database management system and the IBM WebSphere application server.