Asks for the level of ANTRQST that is installed on the system.
,RETINFO=retinfo
is the name (RS-type) (or address in register (2)-(12) ASM
only) of a required 100-character output field used to return the
level of ANTRQST installed on the system. If ANTRQST is not installed,
return code 7000 (RQST_PC_NUMBER_ZERO - see ANTRQSTL) is returned
in register 15 and placed in the RETCODE area, if specified. If ANTRQST
is installed, a level value is placed in the first 4-bytes of the
RETINFO field. This level value indicates which ANTRQST functions,
keywords and parameters are supported. For more information about
the LEVEL request output, see the prolog comments in the ANTRQSTL
macro (shipped with the ANTRQST macro).