INFDS Input/Output Feedback Example

To specify an INFDS which contains fields in the input⁄output feedback section, you can make the following entries:
  • Specify the INFDS keyword on the file description specification with the name of the file information data structure
  • Specify the file information data structure and the subfields you wish to use on a definition specification.
  • Use information in the Information Center to determine which fields you wish to include in the INFDS. To calculate the starting position and length of the subfields of the input/output feedback section of the INFDS, use the Offset, Data Type, and Length given in the Information Center and do the following calculations:

       Start = 241 + Offset
       Character_Length = Length (in bytes)

    For example, for device class of a file, the Information Center gives:


       Offset = 30
       Data Type is character
       Length = 2

    Therefore,


       Start = 241 + 30 = 271

    See subfield DEV_CLASS in the example below

Figure 1. Example of Coding an INFDS with Input/Output Feedback Information

   DCL-F MYFILE WORKSTN INFDS(MYIOFBK);

   DCL-DS MYIOFBK;
                                           // 241-242 not used
     WRITE_CNT     INT(10)    POS(243);    // Write count
     READ_CNT      INT(10)    POS(247);    // Read count
     WRTRD_CNT     INT(10)    POS(251);    // Write/read count
     OTHER_CNT     INT(10)    POS(255);    // Other I/O count
     OPERATION     CHAR(1)    POS(260);    // Current operation
     IO_RCD_FMT    CHAR(10)   POS(261);    // Rcd format name
     DEV_CLASS     CHAR(2)    POS(271);    // Device class
     IO_PGM_DEV    CHAR(10)   POS(273);    // Pgm device name
     IO_RCD_LEN    INT(10)    POS(283);    // Rcd len of I/O
   END-DS;