Task: An instance of the execution of a particular transaction type is a task. That is, one execution of a transaction, with a particular set of data, usually on behalf of a particular user at a particular terminal. By pressing a terminal key, a transaction is triggered. Subsequent to the processing, the results are sent back to the terminal based on which the user responds by keying in additional data.
The difference between a task and transaction is shown above. Visualize a Library Information System. To add a new book, a record is to be added into the book-master database.
Normally a transaction will be used for performing this operation. It is possible that several users may work at several terminals at the same time and add different book records to the master. All these users will use the same transaction, but CICS initiates a different task for each one of them. CICS provides for concurrent execution of multiple tasks, including tasks of the same type, like Order Entry.
Multi-threading - Ability to use only one copy of the program when more than one task of the same type is active thereby minimizing main storage. Each task will acquire a working storage section; however all the tasks will use the same load module. This feature is called multi-threading.
Since several tasks can be running at the same time, CICS is a multi-tasking system. Once the program finishes executing, the working storage for that user is released and the virtual memory that was used is free to be allocated to another user. Re-entrant — The ability of the program to enter itself without any modifications. The terminal is a character based terminal displaying 24 lines 80 characters each. In order to display the data contents on a terminal, the terminal must receive the information in a series of data stream.
For the family of devices, this stream is known as the data stream. The data stream is a mixture of control characters known as BCC and text data.
To relieve the task of building and decoding complicated strings of control characters and data, and to remove device dependant codes from the application programs, CICS provides a facility known as the Basic Mapping Support BMS. BMS is an interface between the application program and the terminal control. BMS allows to create a Map that specifies the format of data as it appears on the terminal device.
You can use terminals or emulation, the CICS application provides both the presentation logic and the business logic. In this case, the user interface is text only, not graphical. In other words, the period between the start of a particular set of changes and the point at which they are completed is called a logical unit of work LUW. Synchronization Point : The end of a logical unit of work is indicated to CICS by a synchronization point abbreviated to syncpoint.
It lets you send text or receive text from the terminal that initiated the task. Some of these access methods can also be used in combination with each other. Basic mapping support BMS provides the interface between application programs and terminal control.
It lets you create maps that specify the position and the characteristics of the individual display elements on the terminal screen. As a result, you can create interfaces that are easy for users to work with. Each terminal in this table is assigned a unique one- to four-character terminal identifier, or term-id. Till such time, the resources allocated to the task will have to be retained by CICS. A few such tasks will result in CICS going short of main storage allocated to it, thus affecting overall system performance.
It then suspends that task and releases its resources. This is called pseudo-conversation. Pseudoconversational programs are more efficient than Conversational programs but involve a bit of programming. Together with BMS support, terminal control provides an application program, the ability to communicate with a terminal. The relation between the txn id and the entry program should be defined here.
All the files used by the application program should be registered in FCT. System log file and other user journal files should be registered in JCT. Generally, there is only one copy of a program in storage, and many end users can be executing it simultaneously. If specified on the trace options, each CICS command that is called by the application program, causes entries to be written to the trace table. EDF - In this case, you can stop the flow of the program at specified points, examine data areas, and if necessary, alter them.
The program can be closely monitored, and the errors can be eliminated online. The transient data program stores records in the order that the program writes them, in a sequential queue for each defined queue, called a Transient Data destination. Transient data has two types of queue: 1. For example, a file on tape or on disk accessed by tasks CICS, can subsequently be read by a batch program and vice versa.
If found, CICS gets the transaction details like program-id, security aspects, etc. If not, it generates an error and abends the transaction. It then transfers control to the application program. If the program is already resident in main memory, CICS uses the same but with a separate working storage for this transaction. Otherwise, it is loaded into main memory. IT management and business executives view CICS as an indispensable middleware productivity tool that is essential in their transaction processing environment.
Application programmers use an extensive application programming interface API to write programs to process user requests. Terminal users enter CICS transaction to run online applications.
Notes: It is essential to know the difference between a transaction and a task and it may be worth reviewing this topic. Melissa Steele Dec. No problem. Shoaib khan Dec. Using autoinstall for programs can save time spent on defining individual programs, mapsets, and partitionsets. Savings can also be made on storage, because the definitions of autoinstalled resources do not occupy space until they are referenced. Use of autoinstall for programs can reduce the number of definitions to be installed on a COLD start, thereby reducing the time taken.
Decide which programs to autoinstall. Depending on your programs, you can choose to use a mixture of RDO and autoinstall. A suggested way to manage program autoinstall is to continue to use RDO for existing program definitions and for installing groups containing related programs. Use autoinstall as you develop and install new applications, and in test environments, where you might otherwise install large numbers of programs at CICS startup. Furthermore we can assign the programs to a group, clustering transactions, maps, and programs together.
Usually when you use a new program you will also use a new transaction, which probably will involve RACF entries. It depends on site policies, etc. New programs are really not that often, at least not in our shop. But help me out here, do you mean if your program is coming via program autoinstall than it will not show up in CICS regions statistics. If you have a program that is not being used it will not be auto installed and therefore it will not appear in your CICS statistiks. How are you going to determine if the program is a CICS program, if it has been used, will be used, has never been used?
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