16.20 - Changing the Value for Use-presence-bits - Teradata Tools and Utilities

Teradata® Call-Level Interface Version 2 Reference for Mainframe-Attached Systems

Teradata Tools and Utilities
September 2019
Programming Reference
When the value for Use-presence-bits is not appropriate for the application, you should perform the following procedure before calling DBCHCL for the following functions:
  • Connect
  • RunStartUp
  • Initiate with Protocol-function
  • Initiate Request
  1. Set Change-options to 'Y'.
  2. Change the value for Use-presence-bits as follows.
    If the data string has been prepared in this mode... Then change the value for Use-presence-bits to...
    indicator (IndicData) Y
    record N

Use mnemonics for the codes. Mnemonics are provided in the language definition file for the DBCAREA.

To send null data to Teradata Database, set Use-presence-bits to 'Y' and provide a data string as described for the IndicData parcel.

Since DBCHCL does not parse the request string, it is the responsibility of the application to check whether the request string contains a USING row descriptor and to set Use-presence-bits, USING-data-pointer, and USING-data-length appropriately.

See Varying-length-request, for the preparation of the input data string: the order of the two-byte length field (if used), the bytes containing indicator bits (if used), and the bytes containing data values.

Although Use-presence-bits is read during the call to DBCHCL for the Connect function and the RunStartUp function and is stored in the appropriate session and Request Control Blocks, it is not usually used by the functions. Neither function sends an input data string to the Teradata software, unless a macro that accepts the Use-presence-bits parameters is set up for the RunStartUp function.