You don't need a trigger. We also just have a basic index defined. Can be anything.
Something like this:
CC=YES
CCTYPE=A
CONVERT=NO
CPGID=500
MCF2REF=CPCS
TRC=NO
FILEFORMAT=RECORD,256
FIELD1=X'C3C9C3E240C4C5C6C9D5C9E3C9D6D5E240D9D7E37A40D7C4C5E54040C7F8F6F3'
INDEX1=X'D985979699A36DD5819485',FIELD1,(TYPE=GROUP,BREAK=NO) /* Report_Name */
DCFPAGENAMES=NO
UNIQUEBNGS=YES
IMAGEOUT=ASIS
INDEXOBJ=ALL
INDEXSTARTBY=1
INSERTIMM=NO
RESTYPE=NONE