Solution : https://service.sap.com/sap/support/notes/1056472 (SAP Service marketplace login required)
Key words : 
sap nw rfc sdk solves, underlying tcp/ip connection, managing abap exception descriptions, sap nw rfc sdk, underlying rfc connection breaks, backend system whithout closing, nw rfc library, enhanced trace functionality, transaction handle leads, required buffer length
Related Notes : 
       
| 1025361 | Support and Availability of the SAP NetWeaver RFC Library |