The Traceback facility for VSI OpenVMS Integrity servers and
    Alpha systems is a debugging tool that provides information
    (symbolizations) about call stack PCs. In normal operation, when
    a process suffers a fatal unhandled exception, the operating
    system launches Traceback which sends to SYS$OUTPUT the complete
    call stack at the time of the exception. Applications can also
    directly use the Traceback facility to sequentially generate
    information for an individual call stack PC. In this case,
    the Traceback simply returns information to the caller, not to
    SYS$OUTPUT. The links below describe the routines for using this
    direct Traceback interface. On Integrity server systems, the
    routine is called TBK$I64_SYMBOLIZE and on Alpha systems, it is
    called TBK$ALPHA_SYMBOLIZE. Choose the appropriate TBK routine
    for your platform.