If the iServer is running on a Windows platform, the computer’s application code page must match the DB_LOCALE of the Informix server. For example, if the database character encoding is Japanese (Shift JIS), the application code page of the computer on which the iServer is running must be Japanese (Shift JIS). In other words, you must set CLIENT_LOCALE to ja_JP.sjis-s.
If the iServer is running on a UNIX platform, you must provide a value for the IANAAppCodePage property. If you do not set IANAAppCodePage, the database driver searches for a value in the system information file (odbc.ini), first in the Data Source section and then in the ODBC section. If the database driver does not find a value in odbc.ini, it sets IANAAppCodePage to 4 (ISO 8859-1 Latin-1).