On the client side or database server side, the locale is established with the following precedence of announcement mechanisms, the CLIENT_LOCALE, LANG, LC_*, and the English locale, en_US.8859-1. Given this precedence, the six categories of the processing locale are set in the following way: COLLATION, CTYPE, TIME, MONEY, NUMBER, MESSAGES.
The GLS initialization function returned this error because an invalid locale was specified. The locale specifier is usually the environment variables. Check the value of INFORMIXDIR and CLIENT_LOCALE. INFORMIXDIR should point to a valid directory where the IBM Informix products are installed. This directory should also contain the /gls directory where the locale and code-set files reside.