Solution : https://service.sap.com/sap/support/notes/548943 (SAP Service marketplace login required)
Key words : 
reorganization -> analyze table report -> list tables, terms frequently asked questions, prevent disk space problems, disk space problems exist, user-defined page size, free disk space consisting, bw-specific performance notes, impending space problems, disk space problems, oncheck -pt <sid>
Related Notes : 
       
| 556729 | L statistics runtime problems with database INFORMIX | 
| 181945 | Performance guide: BW on Informix | 
| 178012 | INF-271 without ISAM code | 
| 85067 | Accelerating 'Create index' using PDQ | 
| 83183 | Fragmentation: Basics - decision help | 
| 81642 | Frag./detached index: Special behavior in R3 | 
| 79191 | Creating 'detached indexes' | 
| 79070 | Table fragmentation: procedure | 
| 64001 | INFCFGCHECK: Detailed messages of single checks | 
| 62340 | INFCFGCHECK: 'Download' and 'First steps' | 
| 44591 | You cannot create new chunks | 
| 29413 | Extending the logical log | 
| 29381 | inf458 "Long transaction aborted." | 
| 22941 | Reorganization of tables and dbspaces! | 
| 17947 | How can you determine the current extent size ? | 
| 13142 | Defining additional storage areas under INFORMIX | 
| 3397 | INF131, INF271, INF603: No free disk space |