Online systems provide users with immediate access to the information they need to do their work. It is important that as a DB/DC control system CICS provide consistent and reliable access to that data. In order to meet this goal online system development must provide for the handling of errors that would result from power failure, system crash, or program abends, etc. So it is crucial to recover the resources and to restart the transactions or the entire system as quickly as possible. The goal of recovery processing is to:
The issue of recovery must be addressed throughout the system development life cycle, beginning in the early stages of design. Since recovery processing may have an effect on the performance of a system, it should be planned carefully to minimize the impact on system users.
CICS continually records information about the state of the region and about the state of each unit of work in the region. This information is preserved and used when a region is restarted, thus enabling CICS to restart with no loss of data integrity.
If CICS shuts down leaving any units of work in-flight, these units of work are backed out when CICS restarts and locks held by these units of work are released.
A CICS region can shut down in several ways:
Normal (or warm) shutdown
The CICS region shuts down in response to a CICS system management command. All transactions that have already started continue to run, and CICS waits indefinitely until they are complete. Long-running transaction can cause an unacceptable delay, or require intervention by the operator.
The CICS region shuts down in response to a CICS system management command. All transactions are purged from the system; units of work are not backed out, and locks are not released, until the region restarts.
The CICS region shuts down in response to an unrecoverable error in a CICS system module, in response to a request from the operating system (arising, for example, from a program check or system abend), or following a machine check or power failure. In an abnormal shutdown, CICS might not be able to perform any shutdown processing. Units of work are not backed out and locks are not released until the region restarts.
Depending on whether the region has been started and shut down in the past, and on the way it was shut down, a CICS region can start in several ways:
The CICS region starts with no reference to any previous activity. You perform an initial start when starting a new CICS region for the first time.
The CICS region starts and restores recovery information that relates to systems and resource managers that were connected when the regions shut down. It does not recover the state of local resources.
A warm restart follows a normal shutdown and restores the region to its state it was in when shutdown completed.
An emergency restart follows an immediate or abnormal shutdown of the CICS region. During an emergency restart, CICS backs out any transactions that were in-flight at the time of shutdown and thus frees any locks that were held at the protecting resources.
In normal operation, when a CICS region starts, it examines the information recorded before the region last shut down to determine in which way to start.
IBM Mainframe Related Interview Questions
|IBM Lotus Notes Interview Questions||IBM-CICS Interview Questions|
|COBOL Interview Questions||Linux Interview Questions|
|IBM-JCL Interview Questions||IBM Mainframe Interview Questions|
|IBM AIX Interview Questions||IBM WAS Administration Interview Questions|
|IBM Lotus Domino Interview Questions||IBM Integration Bus Interview Questions|
|Mainframe DB2 Interview Questions||Unix Production Support Interview Questions|
Ibm Mainframe Tutorial
Introduction To Software Development
Introduction To Ibm Mainframes
Tso And Ispf
Jes2, ]es3 And Sms
Introduction To Job Control Language (jcl)
The Job Statement
The Exec Statement
The Job And Exec Statements
The Dd Statement
Procedures And Symbolic Parameters
Generation Data Groups (gdg), Compile/link-edit And Run Jcls
Access Method Services (ams)
Additional Vsam Commands
Introduction To Rexx
Overview Of Rexx
Introduction To Cics
Exception Handling In Cics
Developing A Cics Application
Cics Programming Techniques
Basic Mapping Support (bms)
Transient Data Control
Temporary Storage Control
Interval And Task Control
Cics Application Design
Recovery And Restart
System Security And Intersystem Communication
Cics Debugging Facilities And Techniques
Bms Map Definition Macros And Copylib Members
Cics Response And Abend Codes
Data, Information And Information Processing
Introduction To Database Management Systems
Introduction To Relational Database Management Systems
Database Architecture And Data Modeling
Overview Of Db2
Structured Query Language (sql)
Data Security And Access
Db2 Application Development
Qmf And Db2i
Db2 Performance Monitoring, Utilities And Recovery/restart
Overview Of Information Management System (ims)
Introduction To Vs Cobol Ii
Overview Of Application Development In Vs Cobol Ii
Overview Of The Cobol Program
Sorting And Merging Files
Coding Cobol Programs That Run Under Cics. Ims, Db2 And Ispf
Compiling The Program
Link-editing The Program
Executing The Program
Improving Program Performance
All rights reserved © 2018 Wisdom IT Services India Pvt. Ltd
Wisdomjobs.com is one of the best job search sites in India.