See link https://www.ibm.com/docs/en/i/7.6.0?topic=ssw_ibm_i_76/rzaha/stdiosys.html
QIBM_RPG_JAVA_PROPERTIES - set os400.stdio.convert=N
Also available for child properties **os400.child.stdio.convert **
Pre create and pre-open your file and set the CCSID to 1202 for UTF8 for example.