ircII help: set log

Usage: SET LOG [ON|OFF|TOGGLE]
  Turns the session log ON or OFF.  While ON, a record of your
  IRC session is recorded to file (see HELP SET LOGFILE).  When
  OFF, no log is made.  This log will contain everything that 
  appears on your screen, no matter what window, in the order it
  comes in.  To log an individual window, use the: 
    WINDOW LOG [ON|OFF|TOGGLE]
  command.

See Also:
  SET LOGFILE
  WINDOW LOG
  WINDOW LOGFILE