The defeucw option to the /bin/stty command is for modifying STREAMS modules to reflect changes in the user's environment. It does not work with the /usr/ucb version of stty, which has not been internationalized.
The following command queries the user's environment for information on EUC code set width and sets.
system% /bin/stty defeucw
For example, if the user has the environment variable LC_CTYPE set to locale, this option gets information on the number of bytes per character and the screen width per character for the code sets in the ko and ko.UTF-8 environments and then sends this information to relevant modules in the stream.