Solution : https://service.sap.com/sap/support/notes/785365 (SAP Service marketplace login required)
Key words : 
620 patch level 1729640 patch level 44for higher kernel releases, terms memory management reason, single large user context, parameter values em/global_area_mb, prerequisites extended global memory, extended global memory, cross-session data, internet transaction server, platform-dependent settings, requested segment size
Related Notes : 
       
| 923610 | Memory parameter recommendations for banking systems | 
| 788963 | CST Patch Collection 46 2004 | 
| 326949 | Shared Memory Management z/OS Application Server |