Multithread programs have multiple threads of execution within a
  process and include the following:

   -  Programs written in any language that use DECthreads or POSIX
      1003.1b services.

   -  Programs that use language-specific threads services (services
      provided directly by the language).  Currently, Ada is the only
      language with built-in threads services that the debugger supports.

  Within the debugger, the term thread or task denotes such a flow of
  control regardless of the language or implementation.  The debugger's
  threads support applies to all such programs.

  The debugger lets you display thread information and modify task
  characteristics to control thread execution, priority, state
  transitions, and so on.

  The following paragraphs summarize the multithread features of the
  debugger's DECwindows Motif interface.  For more information about the
  debugger's threads support, see the manual provided with this debugger.

  Displaying Information about Threads:

  To display information about one or more threads of your program,
  choose Views...  from the Options menu on the main or optional view
  window.  When the Views dialog box appears, click the button for
  Threads.  The Threads View dialog box is displayed.

  The thread view gives information about all currently existing
  (nonterminated) tasks of your program.  The information is updated
  whenever the debugger regains control from the program.

  The displayed information includes:

   -  The Thread ID.  The arrow in the left column marks the active
      thread, that is, the task that runs when you click on the Go or
      Step push button.

   -  The current state of the thread.  The running thread (thread in the
      RUN state) is the active thread.

   -  Whether the thread has been put on hold.

   -  The thread priority.

   -  The current substate of the thread.  The substate helps indicate
      the possible cause of a thread's state.

   -  A debugger path name for the thread object or the address of the
      thread object if the debugger cannot symbolize the thread object.

  Changing Thread Characteristics:

  To modify thread characteristics or the thread environment while
  debugging, choose one of the following items from the Threads menu on
  the optional view window:

  Action      Function
  ------      --------

  Abort       Requests that the selected thread be terminated at the
              next allowed opportunity. The exact effect depends
              on the current event facility (language dependent).
              For Ada tasks, this is equivalent to executing an
              abort statement.

  Activate    Makes the selected thread the active thread.

  Hold        Places the selected thread on hold.

  Nohold      Releases the selected thread from hold.

  Make        Makes the selected thread the visible task.
    Visible

  All ->      Uses the submenu to:
                 Abort all threads
                 Hold all threads
                 NoHold all threads

  To save these modifications for subsequent debugger sessions, choose
  Save Options from the Options menu on the main or optional view window.
  This creates a new version of the debugger resource file with the new
  definitions.