Your program can call a system service that returns the information that the access method services LISTDATA command returns. This information is subsystem statistics, status and count information. To obtain this information, your program must be APF-authorized. Your program will call IDCSS01 with the LINK macro. You pass to IDCSS01 a three-word parameter list pointed to by register 1. If your program is not authorized and attempts to link to IDCSS01, the system issues ABEND with system code 047. The following shows an example of the IDCSS01 call:

         ST    R5,AddrSGARGL        Set address of SSGARGL
         LINK  EP=IDCSS01,PARAM=(,MyArgL,MyRetCode)   Call LISTDATA
         SR    R15,R15              Prepare for ICM
         ICM   R15,B'0011',MyRetCode  Obtain and test return code
         BNZ   ListDataFail         Branch if call failed
         . . .
MyArgL   DC    A(AddrSSGARGL)       Address of SSGARGL address
AddrSGARGL DC  A(0)                 Address of SSGARGL
MyRetcode DC   H'0'                 Return code from service
         IDCDF70 ,                  Map the parameter list