Solution : https://service.sap.com/sap/support/notes/1405464 (SAP Service marketplace login required)
Key words : 
tid encountered [null], hostname 'xxxxxxxx' unknown, function module invocation, ascii/ebcdic conversion, conversion reason, ebcdic variant, synchronous call, incorrect size, sap system, communcation fails
Related Notes : 
       
| 1438294 | SAP Java Connector Release 3.0.5 | 
| 1406061 | z/OS: JCo 3.0.3: ERROR hostname unknown | 
| 1385673 | SAP Java Connector Release 3.0.3 | 
| 1375494 | SAP system does not start after applying SAP kernel patch | 
| 1077727 | SAP JCo 3.0 release and support strategy |