Solution : https://service.sap.com/sap/support/notes/1422790 (SAP Service marketplace login required)
Key words : 
iso8859-1' lang='d' country='   ' codepage='1100', environment variable sap_locales, country setting, textenv_invalid environment, sap system, error message, locale='de_de, os400 reason, sar patch 70, set incorrectly
Related Notes : 
       
| 1423602 | IBM i: Problems with locales in 7.01 |