When the traceback display appears, you identify the traceback entry
  most closely associated with the segment you are investigating.  Most
  often, you can do this by comparing segment type names and traceback
  routine names.

  When you double click MB1 on this traceback entry, the source code
  associated with the entry appears (highlighted) in the Source Window.
  You can then scroll through the source code display, identify
  problematic code, and decide how to correct it.

  If you cannot identify any problems in the displayed source code,
  return to the Information Window and double click MB1 on the routine
  immediately above or below your previous choice.

  If you double click MB1 on a traceback entry, and 'Source Not
  Available' messages appear in the Source Window, you may have forgotten
  to set a source directory at the beginning of your heap analyzer
  session.  See the 'Setting a Source Directory' help topic for
  information on setting a search directory.