Solution : https://service.sap.com/sap/support/notes/634007 (SAP Service marketplace login required)
Key words : 
code page convert cache reason, code page converter, krn/rscp/rscpc, local cache, function rscplengthofbasicchar, patch level  988, note 447519 package 24, semaphore 12 belongs, semaphore 12, prerequisites
Related Notes : 
       
| 447519 | Kernel patches for code pages, languages and locales |