VMS Help V73 Features, Programming Features, SDA Commands for Spinlock Tracing, SPL_UNLOAD  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    This command unloads and cleans up the SPL$DEBUG execlet. Tracing
    is automatically disabled and the trace buffer deallocated. It
    has no qualifiers.

    For more information, refer to the OpenVMS Alpha System Analysis
    Tools Manual.