Use CREATE DATABASE

A database is a container that holds all parts of a data model. These parts include not only the tables but also views, indexes, synonyms, and other objects that are associated with the database. You must create a database before you can create anything else.

When the database server creates a database, it stores the locale of the database that is derived from the DB_LOCALE environment variable in its system catalog. This locale determines how the database server interprets character data that is stored within the database. By default, the database locale is the U.S. English locale that uses the ISO8859-1 code set. For information about how to use alternative locales, see the Informix® GLS User's Guide.

When the database server creates a database, it sets up records that show the existence of the database and its mode of logging. These records are not visible to operating-system commands because the database server manages disk space directly.