Solution : https://service.sap.com/sap/support/notes/1017718 (SAP Service marketplace login required)
Key words : 
create index <mylib>/<myindex>, including  i5/os v5r3, r3<sid>data/atab, r3<sid>data /, i5/os v5r3, i5/os v5r4, noticebly affects performance, classic query engine, sql query engine, table pool atab
Related Notes : 
       
| 822296 | Additional info: Upgrade to SAP NW 2004s AS ABAP (iSeries) | 
| 68732 | AS/400: IBM tools DSPSTMF, SQLUTIL.. |