Solution : https://service.sap.com/sap/support/notes/205220 (SAP Service marketplace login required)
Key words : 
stack free  id                    kb          kb, apo system start 38 work processes, control       param_startsession       param_put maxusertasks <, livecache core parameter maxusertasks, free database session, control show storageexample, task  type     stack, 17 err     0 sapdberr assertion, 17 err 11196 dbcrash  vabort, 40  12 err 53000 object   bd930
Related Notes : 
       
| 593154 | CCMS alarm : number of user tasks in Connect Wait status | 
| 500843 | Composite SAP note for COM and SAP liveCache 7.2 or higher | 
| 487972 | Operating system parameterization of liveCache | 
| 433115 | Parameterization of liveCache 7.2 for APO 3.0 |