Solution : https://service.sap.com/sap/support/notes/132982 (SAP Service marketplace login required)
Key words : 
'alter table <tabname> alter <columnname> set data type <datatype>'statement, 'alter table <tabname> alter <columnname> set data type <datatype>', directory ~general/r3server/patches/rel45b/<unix/nt>/<aix/i386>/db2, ~general/r3server/patches/rel45b/<unix/nt>/<aix/i386>, kernel cd /<sapcd1>/os390/fixesto /usr/sap/put/bin, 'illegal symbol <columnname>'            apar pq20644 prevents indexes, sapservx directory ~ftp/general/r3server/abap/note, adjust file /usr/sap/put/bin/r3curenv, file /usr/sap/put/bin/append, file '/usr/sap/put/bin/tpparam'
Related Notes : 
       
| 306908 | DB2/390: Primary index created without CLUSTER | 
| 204577 | DB2/390: R3load terminates with 'core' during R3up | 
| 151833 | Additional Info: Upgrading to FCS 4.5B | 
| 151394 | DB2/390: Transports for 4.5B | 
| 132305 | DB2/390: Upgrade: Create INDEXES with DEFER YES | 
| 117668 | Additional info: Upgrading to 4.5B | 
| 81737 | DB2-z/OS: APAR List |