Topics:

• Fast Path Considerations
• The PSB PROCOPT to Use With the Adapter
• Access to IMS Through DBCTL
• Access to IMS Through the XMI Server
• Access to IMS With FOCUS Loaded by the Region Controller
• Summary Chart
• Environment Switching

IMS can run in several different environments and with various options. This chapter describes each environment and illustrates how to invoke the Adapter for IMS/DB from it. Regardless of which environment you use, the capabilities of the adapter are the same.

From the FOCUS perspective, three configurations are available:

• FOCUS can run in the same address space as an IMS component called the DBCTL stub and communicate directly with online IMS databases in a second address space. You implement this environment in your FOCUS session with SET commands. See Access to IMS Through DBCTL for information about the DBCTL environment.
• FOCUS can run in a separate address space from all IMS components and pass its DL/I calls to the IMS region controller (DFSRRC00) in a second address space.

  To initiate this configuration, you execute program DFSRRC00. This region controller program then loads the XMI server (program XMI). After the XMI server is loaded and executing, you can invoke the adapter from a CLIST or batch JCL. In order for the FOCUS address space to communicate with the region controller address space, you must allocate a common communication file in each. See Access to IMS Through the XMI Server for information about the XMI server environment.

• FOCUS can run in the same address space as the IMS region controller.

  To invoke the adapter with this configuration, you execute program DFSRRC00 (for IMS). This region controller then loads FOCUS.

  Access to IMS databases with this configuration is quick, eliminates the separate FOCUS address space needed with the XMI server, and does not require you to allocate a communication file. IMS must allow shared access to the databases. See Access to IMS With FOCUS Loaded by the Region Controller for information about this environment.

Access to IMS Through DBCTL, Access to IMS Through the XMI Server, and Access to IMS With FOCUS Loaded by the Region Controller discuss each environment and provide CLISTs and JCL for invoking the adapter. For your convenience, Summary Chart contains a chart that summarizes the environments available with the adapter, including the advantages and disadvantages of each. Environment Switching explains how you can change from one environment to another within your session.