12 zSeries Application Assist Processor (zAAP) Implementation
running on a distributed platform which has the specific resources required by the
CICS application.
1.5.8 IMS
The transaction processing strengths of IMS in an enterprise computing environment are
appreciated and exploited worldwide. IMS has always provided a robust transaction
processing environment that:
򐂰 Allows creation of transactions with atomicity, consistency, isolation, and durability (ACID)
properties.
򐂰 Allows transactions to run under all sorts of conditions.
򐂰 Provides continuous operation and high availability with (more recently) sysplex support,
data sharing, and the removal of single points of failure.
IMS Java allows IMS shops to take advantage of the growing pool of Java-trained
programmers. It extends existing IMS transactions to e-business, uses Java with
high-performance server solutions, and reduces the complexity of IMS application
development. IMS Java was developed to provide an application programming interface that
is usable by experienced Java programmers, and to provide an API that can later be
supported with code generation tools, such as those found in VisualAge® for Java. IMS Java
provides you with the ability to develop new applications more easily. IMS Java also provides
Java programmers with complete access to necessary IMS services.
IMS Java is delivered in a layered set of class libraries providing high-level classes that focus
strongly on ease-of-use, and lower-level classes that provide complete access to IMS
services and serve as the implementation vehicle for the higher-level classes.
The IMS Java classes allow you to write the following types of applications:
򐂰 Message Processing Programs (MPPs)
򐂰 IMS Fast Path Programs (IFPs)
򐂰 Batch Message Processing Programs (BMPs)
1.6 zAAP workflow
When a z/OS logical partition is configured, both CPs and zAAPs are defined as necessary to
support the planned Java and non-Java workloads. zAAPs may be configured as initially
online or reserved for subsequent use by z/OS as necessary. As previously stated, zAAPs
cannot be IPLed, and at least one central processor is required for each z/OS partition.
zAAPs may be defined as either shared by other logical partitions or dedicated to a specific
partition; however, both central processors and the zAAPs for each partition will have the
same shared or dedicated attribute. For a given partition, you cannot define shared central
processors and dedicated zAAPs or dedicated central processors and shared zAAPs. PR/SM
configures shared zAAPs from the same pool of shared special purpose processors as ICFs
and IFLs. Collectively, all shared ICFs, IFLs, and zAAPs will also dynamically share in the
processing requirements for all three special purpose processor types as controlled by
PR/SM.
1.6.1 Java execution flow
Integrated Facility for Applications (IFA) eligible work can run on both IFAs and standard
processors. There are options that specify how the Java execution cycles are dispatched.

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