In any CICS program processing input instructions from terminal is major task.
CICS is OLTP, like web application, we give input from the screen and we get output. Apart from this from the main screen we can navigate other screens.
This is called screen navigation.
We need to do mapping design as a first task.
In the application program we can process it by using Handle Aid:
EXEC CICS HANDLE AID PA1(LAB1) ANYKEY(LAB2) PF10
If a task is initiated from a terminal by means of an AID, the first RECEIVE command in the task does not read from the terminal but copies only the input buffer, so that control can be passed by means of a HANDLE AID command for that AID.
The EIBAID field in the EXEC Interface Block (EIB) holds a code for the attention identifier that is associated with the last terminal control or Basic Mapping Support (BMS) input operation. To simplify testing the contents of the EIBAID field in your application program, CICS® provides a copy book that contains a list of symbolic names that are associated with the attention identifier constants.