Solution : https://service.sap.com/sap/support/notes/1460139 (SAP Service marketplace login required)
Key words : 
terms lib_dbsl xdn directdrive reason, aix application server, follow sap note 146624, configuring database multiconnect, latest lib_dbsl, symptom db4, data source, db2/400 solution, prerequisites, release 640+
Related Notes : 
       
| 1257635 | DB4: DBSL Direct Drive for DB2 for IBM i (DB2/400) | 
| 523381 | BW: External DB connect for an IBM i database | 
| 146624 | i5/OS: Database Multiconnect for IBM DB2 for i5/OS |