Library /sys$common/syshlp/scacp$help.hlb START, TRACE, Qualifiers, /STOP  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /STOP[=(event1,event2,...)]

    Stops tracing on specific events, which you can specify using
    wildcards. The default is to stop no events.

    Use the SHOW TRACE/CONTEXT command to display event names.