DBG$HELP.HLB

1 /START_LEVEL
       /START_LEVEL=n

    Directs SHOW STACK to begin displaying information at call frame
    level n. For example, to see stack information for only frame 3,
    enter the following command:

    DBG>  SHOW STACK/START=3 1

    To see details for the 4th and 5th stack frames, enter the
    following command:

    DBG>  SHOW STACK/START=4 2