VMS Help Sys Parameters, IJOBLIM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    IJOBLIM sets the maximum number of interactive jobs that can be
    on the system concurrently. You can control the maximum number of
    concurrent interactive users on the system with the DCL command
    SET LOGINS/INTERACTIVE.

    IJOBLIM is a DYNAMIC parameter.