CICS Interview Questions

1. Explain the differences between a Transaction and a Task.
Under CICS, a user can't directly invoke a program. Instead, the user invokes a transaction, which in turn specifies the program to be run. When a user invokes a transaction, CICS locates the associated program with the transaction, loads it into storage (if it is not there), and starts a task. Where Task is a unit of work which is scheduled by CICS. The difference between transaction and task is that while several users may invoke the same transaction, each initiates a separate task.

2. Describe the basic differences between batch and online systems.
An Batch processing system handles large amounts of data which processed on a routine schedule. An online processing system handles transactions in real time and provides the output instantly.

3. What are the four major types of Online Programs?
The menu program. The inquiry program. The file maintenance program. The Data Entry program.

4. Describe the different considerations for the Online programs (CICS).
Ease of use, Performance, File Integrity and Security

5. Different between Multitasking and Multi-threading?
Multi-tasking means that the OS allows more than one task to run (be executed) concurrently, regardless of whether the task use the same program or different programs. Multi-threading is the system environment, where multiple tasks share the same program under the multi-tasking environment. Programs are shared by several tasks, and for each task the program work as if it executes the instructions only for that task.

6. Describe the differences between operation of Pseudo-Conversational and a conversational program
In a conversational mode, the program accomplishes the conversation by simply sending a message to the terminal, and waiting for the user to respond, and receiving the response from the terminal. The system that sits idle without allowing an other operation while waiting for the data is called a conversational program. In a Pseudo-Conversational program, a program attempts a conversation with a terminal user, it terminates the task after sending a message with a linkage for the next task. When the user completes the response the next ask is automatically initiated. Pseudo-conversational program's uses the CICS resources such as control tables efficiently.

7. Explain the COBOL code used in a CICS program in general?
There is no difference between the COBOL and CICS Identification Division, in which Program-Id is mandatory. The Environment division of the CICS-COBOL program needs to be empty, as the Environmental information is controlled by the CICS tables such as FCT. Beginning with VS COBOL II Release3 compiler, one can omit coding of the header also. In the Data Division, File Section is not to be defined. It contains the working storage Section and Linkage Section for all the programs. A field called COMMAREA is defined in Working-Storage Section and DFHCOMMAREA in Linkage section for all the programs. Compiler adds Execute Interface Block (DFHEIB) in Linkage section. The Procedure division is used to code the Program logic, to perform the necessary functionality.

8. Explain the COBOL code used to detect the first execution of a program in a pseudo-conversational session. How do you pass information from one task to other? How do you test the response codes?
Evaluate EIBCALEN variable to determine the first execution of a program in a pseudo-conversational session. If it's value is zero then it's the 1st execution of the program. The communication area is a special field, which must be at least of one byte long and is used to pass data from one program execution to the next. The next field defined after the communication area in the working-storage section is the Response field, a full-word binary item (S9(8) comp). This field is used to test the completion status of CICS (READ) command with the option RESP(Response field).

9. What COBOL feature's are not allowed under any compiler version, while coding CICS programs?
ACCEPT, DISPLAY, OPEN, CLOSE, READ, WRITE, REWRITE, DELETE, START, SORT, RELEASE, RETURN, EXHIBIT, TRACE, Segmentation features, and Report writer features. The CICS using COBOL II features that are not allowed under the OS/VS COBOL environment are GOBACK, STOP RUN, EXAMINE, STRING, UNSTRING and INSPECT.

10. What is the importance of MDT in maps?
An MDT on, which is a part of the attribute byte, causes data on the screen to be returned to the program when a map is received. MDT's can be turned on by Specifying FSET as part of the attribute of the BMS map, then issuing a SEND which includes the physical map. Do not overlay the BMS map's attributes with the symbolic map attributes on a SEND of map and data. Symbolic map's attributes equal to low values will not overlay the BMS attributes. Ex. ATTRB=(ASKIP,FSET). Moving a standard attribute, which contains FSET to the Symbolic map's attribute before issuing the SEND which includes the symbolic map, such as MOVE UNPROT-FSET TO MAPFLDA. Keying data into Unprotected field on the screen. Entering data into a field will turns its MDT On.

11. Explain the function of Modified Data tag. List the Extended attributes with stress on highlighting?
Last bit of the attribute byte indicates MDT. If the user keys in any data into the field, it turns the MDT ON indicating that the data is modified. To save transmission time , 3270 terminal sends a field over the TC line only if the MDT is on. Otherwise, the field value is not transmitted. The extended attributes of a field include extended Color (Red, blue, pink, green, turquoise, yellow, white), extended highlighting (Blinking, Reverse Video, Underline), Validation (Must fill, Must enter, Trigger), and Programmed symbols (Up to six alternative user defined char-sets).

12. What is the special byte described at the end of the Unprotected fields in BMS maps called?
The Special byte unnamed fields on a Map are called stopper fields. The others are Unnamed fields (Literal's) are used for Titles, Field identifiers and messages and the Named (variables) Output fields and Named Input fields. There's a stopper field at the end of every named field.

13. Define BMS Map?
The primary objective of Basic Mapping Support system is to free the Application Program from device dependent codes and Format. A screen defined through BMS is called a Map. There are two type of maps.

14. Define Mapset?
Representation of one screen format is called Map. A group of maps, which are link-edited together is called a Mapset.

15. Define Physical Map?
It is the assembly language program, which are created and placed in a load (program) library. It controls the screen alignment plus sending and receiving of constants and data from and to the terminal, and has the terminal information.

16. Define Symbolic map?
It defines the map fields used to store variable data referenced in a COBOL program. They may be placed by BMS into a Copy library and be added to the Cobol program at the compile time.

17. How do you use extended attributes?
Define EXTATT=YES and the correct terminal type. For CICS V1.7 or later use MAPATTS and DSATTS.

18. What are the 3 working storage fields used for every field on the map? What other fields are generated?
Length field, Flag Field and Attribute field. In addition Input & Output field are also created. Others are extended Color & Extended Highlighting attributes created only if MAPATTS and DSATTS are specified.

19. What are the two outputs created as a result of generation of a Map?
The map copybook (symbolic map) saved in copy lib and the load module (making the physical map).

20. How do you protect a field from being overlaid? What is an attribute Byte?
Using Protected attribute. The Attribute byte defines the display/transmission of field.

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