Some languages, such as Japanese and Korean, require double-byte character sets. If you want to input or see double-byte character sets (DBCS) during your ISQL session, you must enter the following CMS command before starting ISQL:
SET FULLSCREEN ON
The SET FULLSCREEN ON command lets you input DBCS characters in CMS command mode, and allows input and display of DBCS characters in ISQL command and display mode.
If you are not going to work with DBCS, you do not need this command.