Solution : https://service.sap.com/sap/support/notes/122599 (SAP Service marketplace login required)
Key words : 
rdisp/vb_key_comp = /host/synr/wpnr/date/time/stmp/, sapdb01locksize rowlockpart yeslockmax 0ccsid asciibufferpool bp4numparts 4, create type 2 unique index vbdata____0, sap bc database administration guide, bc sap database administration guide, create type 2 unique index vbhdr_____0, create type 2 unique index vbmod_____0, system assigns update log tables, stogroup sapsg01 priqty 36720 secqty 3672, stogroup sapsg02 priqty 36720 secqty 3672
Related Notes : 
       
| 1312704 | DB2-z/OS: Handling of VBDATA (with DB2 v9.1) | 
| 1094550 | Local update and update key in old format | 
| 823245 | DB2-z/OS: Transports & Support Packages (7.0 and higher) | 
| 822248 | DB2-z/OS: Growth of the tablespace of table VBDATA | 
| 493577 | DB2/390: Transports and Support Packages for 6.20 | 
| 480180 | Download and installation of attachments for SAP notes | 
| 427392 | DB2/390: Table tuning after the upgrade | 
| 417920 | DB2/390: Corrections for 6.10 and 6.20 | 
| 191191 | Partitioning update tables | 
| 184399 | DB2/390: DDIC corrections (Releases 4.6A,4.6B,4.6C,4.6D) | 
| 135207 | DB2/390: Partitioning of tables | 
| 118901 | DB2/390: Transports for 4.5A | 
| 116698 | DB2/390: Optimizing Access to Tables VBHDR, VBMOD, VBDATA | 
| 109515 | Update groups for asynchronous updates | 
| 103707 | DB2/390: Transports for 4.0B | 
| 102353 | Update control | 
| 101303 | DB2/390: Transports for 3.1I | 
| 82953 | DB2/390: Tables Isolation and Buffer Pools Tuning |