Solution : https://service.sap.com/sap/support/notes/881833 (SAP Service marketplace login required)
Key words : 
log byk=> current sql statement exceeds, profile parameter dbs/mss/stats_on, stack back trace <     function namekernel32, > stack back trace <     function, find lines likec  get_token, database limit[dbtrtab#3 @ 3918] [dbtrtab      ], symptom unicode sap system, developer trace showsstate dump, getdateformatw<nosymbols>state dump, dbtrtab error log
Related Notes : 
       
| 825146 | Add. info. on upgrading to SAP NetWeaver 7.0 on SQL Server |