Earlier releases of RACF didn't use DES to encrypt passwords. A more primitive "Masking" algorithm was used instead, and a knowledgable user could easily "unmask" the ciphers without the need for dictionary-style attacks. Today, DES is the default, but "masked or "hashed" passwords can still be used.
Many RACF systems still include hashed passwords. PWCHECK reports these cases.
PWCHECK-PRO can list hashed passwords in clear text if needed.