Makes the specified task the active task, which is the task that
    runs when a STEP, GO, CALL, or EXIT command executes. This causes
    a task switch to the new active task and makes that task the
    visible task. The specified task must be in either the RUNNING or
    READY state. When using /ACTIVE, you must specify one task.

    For POSIX threads programs or Compaq Ada on Alpha programs, use
    one of the following alternatives:

    o  For query-type actions, use the SET TASK/VISIBLE command.

    o  To gain control of execution, use a strategic placement of
       breakpoints.

    o  Use the PTHREAD tset -a thread-number command.

    You can get help on POSIX threads debugger commands by typing
    PTHREAD HELP.

    See the Guide to the POSIX Threads Library for more information
    about using the POSIX threads debugger.