ODBC error IM003 in SQLConnect on Siebel Server start

When trying to start Siebel Server on AIX 7.1:

bash-4.3$ start_server all

The following error was found in the log files:

ODBC error IM003 in SQLConnect:
[DataDirect][ODBC lib] Specified driver could not be loaded
(native error 0).
Unable to login using specified ODBC parameters.

The cause of the error was an incorrect LIBATH configuration, where lib32 from Oracle Client was missing.

So I updated siebenv.sh file:

LIBPATH=$LIBPATH:$ORACLE_HOME/lib32:$ORACLE_HOME/lib