Solution : https://service.sap.com/sap/support/notes/799106 (SAP Service marketplace login required)
Key words : 
/os v8 index conversion rebuild pending add column reason, alter index cust_idx add column new_col asc, alter table cust     add column new_col, standard sap ddic functionality, employ table-controlled partitioning, index-controlled partitioning -, column new_col, index cust_idx, prerequisites - solution starting, table cust
Related Notes : 
       
| 728743 | Series z: Release of DB2 V8 for SAP Components | 
| 427748 | DB2-z/OS: CCMS corrections (6.10, 6.20, 6.40, 7.x) | 
| 211492 | Inconsistency between ABAP Dictionary <-> database |