When a database is created, the DB_LOCALE in effect at the time is stored in the system catalog and used throughout the lifetime of the database.
Using DBACCESS, create a new database with DB_LOCALE set beforehand to "EN_US.UTF8".
Specifying UTF8 as the codeset allows the creation of schema objects with names which can contain multibyte characters.
The database locale being used by a database can be viewed in DBACCESS using the menu commands: Database> Info > NLS.
The documentation for Informix GLS states that DB_LOCALE is also used to correctly interpret the locale sensitive datatypes NCHAR and NVARCHAR.
The code set specified in DB_LOCALE specifies which characters are valid in any character column as well as the names of database objects.