For an application to run, the load module has to reside in a data set in a CICS load LIBRARY concatenation.
- The static load LIBRARY concatenation: DFHRPL.
- One or more dynamically defined load LIBRARY concatenation.
- Static LIBRARY concatenation- DFHRPL
- The startup JCL defines the static load LIBRARY concatenation,
DFHRPL, to CICS. DFHRPL contains critical data sets, which must be
available for CICS to start up and run, and application program entities.
When CICS is running, changes to the DFHRPL data set names are not
possible without stopping and restarting CICS. Such changes are not
usually an option in today's continuous availability environment.
DFHRPL data set names must conform to the MVS data set naming convention.
Do not place any CICS® DFHRPL libraries, such as SDFHLOAD, in the extended addressing space (EAS) of an extended address volume (EAV) DASD volume. If DFHLDSVC attempts to access any DFHRPL libraries from the EAS, an IEC142I 113-44 message is issued and the request fails.
- Dynamic program LIBRARY concatenation
- You can define program LIBRARY concatenations to CICS dynamically.
The use of dynamic LIBRARY concatenations provides a number of advantages
for the system programmer and the organization:
- They contain one or more data sets from which program artifacts can be loaded.
- You can bring new applications for deployment into service at any time without affecting continuous availability.
- You can easily withdraw existing applications in dynamic LIBRARY concatenations from service without affecting continuous availability.
- You can install patches to existing applications by installing them in a LIBRARY concatenation with a higher ranking than the existing LIBRARY, without affecting continuous availability.
- You can take offline data sets in dynamic LIBRARY concatenations for compression without affecting continuous availability.
LIBRARY data set names must conform to the MVS data set naming convention and you can use alias data sets.
Do not place data sets in a dynamic program LIBRARY concatenation in the
extended addressing space (EAS) of an extended address volume (EAV) DASD volume. If DFHLDSVC
attempts to access any data sets for dynamic program LIBRARY concatenations from the EAS, an
IEC142I 113-44 message is issued and the request fails.
- SDFHLOAD
- Phase 1 PLT programs
- Non-SMS managed data sets
- Data sets with DISP other than SHR
You can install or create dynamic LIBRARY concatenations as either enabled or disabled.
- Enabled
- When you install or create a LIBRARY with an enabled status of enabled, CICS attempts to allocate and then concatenate the data sets, before finally opening the LIBRARY concatenation. If any of these steps fails, those that had already succeeded are undone and the LIBRARY is installed as disabled. A message indicates the step that has failed.
- Disabled
- When you install or create a LIBRARY with an enabled status of
disabled, CICS does not attempt to allocate or concatenate the data
sets. When the data sets are available and the LIBRARY is ready for
use, perform a SET LIBRARY ENABLED command to allocate and concatenate
the data sets and open the LIBRARY.
If any of the enable steps in the SET LIBRARY ENABLED operation fails, those that had already succeeded are undone and the LIBRARY remains disabled. A message indicates the step that has failed.
The following examples help you to use dynamic program LIBRARY concatenations.
