Runtime options =============== .. index:: library routines, environment variables, OmpSs-2 uses the run-time library routines to check and configure different Control Variables (CVs) during the program execution. These variables define certain aspects of the program and run-time behaviour. A set of shell environment variables may also be used to configure the CVs before executing the program. A list of library routines can be found in chapter :ref:`Library Routines` from this specification. However, some library routines and environment variables are implementation defined and programmers will find them documented in the `OmpSs-2 User Guide `__.