Using character set en_us.364 in Informix database DB_LOCALE
For better or worse (and mostly worse), although some of the files necessary to support en_us.364 are present, the file needed in lc11/en_us is not present.  Thus, you can have de_de.364 or es_es.364 or fr_fr.364 or pl_pl.364 but you can't have en_us.364.

You have a few options at this point.


One is to try downloading the ILS — International Language Supplement.  This has many extra locales in it; it might have en_us.364 (but no promises).
Another is to try copying an existing locale (maybe gls/lc11/fr_fr/016c.lco or gls/lc11/de_de/016c.lco to gls/lc11/en_us/016c.lco. You'd probably want to edit the LANGUAGE and TERRITORY lines.  However, be aware that the French and German locales are different; it will matter which you choose.
Report a problem to IBM Informix Tech Support, requesting the file for gls/lc11/en_us/016c.lco.


I'm not sure which is best.  If the relevant file is in the ILS, then that's simple.  Copying a locale file is mostly straight-forward, but you need to consider what will happen if that's not available.