Solution : https://service.sap.com/sap/support/notes/825276 (SAP Service marketplace login required)
Key words : 
system failed        class     cl_db6_rdi       method    get_reorgchk_table       reason, temporary user table area, cl_db6_rdi get_reorgchk_table reason, type 'user temporary tablespace', minimum page size, system issues, dba cockpit, explain ignores, reopt parameter, long runtime
Related Notes : 
       
| 780546 | DB6: Use of new functions in DB2 V8.2 |