Most companies have a Service Level Agreement (SLA) to their customers. An SLA is usually a commitment by the IT department to all other components in the organization to provide “best practices” and near-total availability of all IT services. Often, that availability promises to be 99 percent or higher. In today’s competitive global economy, downtime isn’t an option.
How do companies achieve this near-perfect environment where access to company data and procedures is delivered without failure? The answer is redundancy, connectivity, and transparency to the application, the system, and the environment. CICS can and does deliver all that and more. It takes planning, resources, and commitment but the payback is immense. This article describes how one CICS customer made the investment and reaped the rewards.
Wachovia Corp., like many other global IT shops, has enormous availability requirements. CICS helps Wachovia deliver superior customer service. To maximize resources and achieve optimum availability and performance, the company decided to implement a full parallel sysplex, including a CICSPlex SM configuration for their online applications. While many components were already in place, Wachovia decided to build a new CICS cloned environment and move applications to the new configuration to make it fully “PLEXed” and positioned for the future.
A great deal of planning needs to be done before any changes begin. One of the major features/benefits of a CICSplex configuration is dynamic routing. If a transaction can be executed on any number of different Application Owning Regions (AORs), then there’s no limitation to a specific region’s availability. An application can be highly available only if it has no affinities to a specific region. The first phase of planning is to identify applications that have affinities, since they can’t fully participate in dynamic routing without addressing the affinities. IBM’s CICS Transaction Affinities Utility is a free utility you can use to perform this search. You can run it with existing application load libraries to identify programs that use restricted commands or commands that produce affinities during execution. The CICS Transaction Affinities Utility Guide (SC34-6251) contains complete instructions.
It’s rare to scan an application and have no affinities, but most affinities can be fixed at the system level. TSQ commands, involving temporary storage utilization, are a common affinity you can easily remove by giving the queue name a unique prefix. Minimal, if any, application changes are required. You can then route this unique prefix to a shared temporary storage server through CICS definitions.
Wachovia CICS systems programmers worked with the application development teams to identify all affinity-free applications—potential candidates for the new configuration. Once they identified applications with affinities and fixed them programmatically or through CICS definitions, they moved on to the next phase, which was building the “cloned” regions for the applications to execute within.
Cloning CICS Regions
The term cloning means to create CICS regions that have all resources any application in that “cloned set” needs to execute.
The first group of regions you can clone are Terminal Owning Regions (TORs); you can do this before the application cloning. TORs can provide maximum availability and participate in parallel sysplex for green-screen transactions by registering all of them to the same VTAM generic resource name.