Grouping with a unique-weight sort sequence table (SRTSEQ(*LANGIDUNQ) LANGID(ENU)).
SELECT JOB FROM STAFF GROUP BY JOB
When using the OPNQRYF command, specify:
OPNQRYF FILE((STAFF)) FORMAT(FORMAT2) GRPFLD((JOB)) SRTSEQ(*LANGIDUNQ) LANGID(ENU)
DB2 UDB for AS/400 could use either index HEXIX or index UNQIX.