Analyzing CICS application processing requirements
IMS supports application programs running in a CICS® environment
Defining CICS application requirements
One of the steps of application design is to decide how the business processes, or tasks can be best grouped into a set of programs that will efficiently perform the required processing.
Accessing databases with your CICS application program
When designing your program, consider the type of data it must access. The type of data depends on the operating environment.
Writing a CICS program to access IMS databases
The types of programs you can use depend on whether you are running in the DBCTL environment. Within the different environments, the type of program you write depends on the processing your application requires. Each type of program answers different application requirements.
Using data sharing for your CICS program
If you use data sharing, your programs can participate in IMS data sharing. Under data sharing, CICS online and BMP programs can access the same DL/I database concurrently.
Scheduling and terminating a PSB (CICS online programs only)
Before your online program issues any DL/I calls, it must indicate to IMS its intent to use a particular PSB by issuing either a
PCB
call or a
SCHD
command. In addition to indicating which PSB your program will use, the
PCB
call obtains the address of the PCBs in the PSB. When you no longer need a PSB, you can terminate it using the
TERM
request.
Linking and passing control to other programs (CICS online programs only)
Use CICS to link your program to other programs without losing access to the facilities acquired in the linking program.
How CICS distributed transactions access IMS
CICS can divide a single, logical unit of work into separate CICS transactions and coordinate the sync point globally. If such CICS transactions access DBCTL, locking and buffer management issues might occur.
Maximizing the performance of your CICS system
When you write programs that share data with other programs (for example, a program that will participate in IMS data sharing or a BMP), be aware of how your program affects the performance of the online system.
Programming integrity and database recovery considerations for your CICS program
IMS provides support for protecting data integrity for CICS online programs
Data availability considerations for your CICS program
The data that a program needs to access may sometimes be unavailable. Use the following functions when data is not available.
Use of STAE or ESTAE and SPIE in IMS batch programs
IMS uses STAE or ESTAE routines in the IMS batch regions to ensure that database logging and various resource cleanup functions are completed.
Dynamic allocation for IMS databases
Use the dynamic allocation function to specify the JCL information for IMS databases in a library instead of in the JCL of each batch job or in the JCL for DBCTL.
Parent topic:
Application programming design