Solution : https://service.sap.com/sap/support/notes/795505 (SAP Service marketplace login required)
Key words : 
process / thread id   <number> = <pid><tid>, terms db6 db2udb udb trap reason, exe <db2 trap file>  >  <output file>, file <output file>, names   db2<number>, db2 processes / threads, trpwhere <number>, trap files, formatted trap, db2dump directory
Related Notes : 
       
| 932918 | DB6: Collect Stack Traces of DB2 Processes | 
| 864555 | DB6: Database crash during SORT or REORG | 
| 101809 | DB6: Supported Fix Packs IBM DB2 for Linux,UNIX and Windows |