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     UNS(10)    POS(243);    // Write count
     READ_CNT      UNS(10)    POS(247);    // Read count
     WRTRD_CNT     UNS(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;