Source : Free On-Line Dictionary of Computing

run-time system
     
         (RTS, run-time support, run-time) Library code
        and processes which support software written in a particular
        language running on a particular {platform}.  The RTS
        typically deals with details of the interface between the
        program and the {operating system} such as {system calls},
        program start-up and termination, and {memory management}.
     
        (1999-07-26)