Identifying your requirements
The degree to which you implement ETO across your IMS installation depends on your installation requirements.
ETO is considered fully implemented when no static VTAM® terminals exist in the system and when the majority of terminals and users are defined using the default logon descriptor and default user descriptor. However, because installations vary in application program dependencies, the cost of fully implementing ETO also varies.
Your installation should determine the extent to which full ETO feature support is required,
based on the following requirements:
- Full user-message security
- Full implementation of ETO is required for full user-message security. In this environment, no node-name user descriptors exist. Any requirements for user structures that the default user structure does not provide must be defined by user descriptors or by the Signon exit routine (DFSSGNX0).
- Dynamic terminal support only
- Only partial implementation is required for dynamic terminal support. You can move network
definition statements from the system definition to ETO descriptor PROCLIB members. Benefits of this
implementation include:
- Fewer system definitions are required in order to maintain network definitions, because you can change descriptors between IMS warm starts.
- Shorter run times are required for system definition, because you do not need to define VTAM terminal networks.
- Improved performance exists for IMS checkpoint and restart, because dynamic terminals and user resources are allocated only when they are used.
With partial implementations, however, you do not achieve improved user-message security, because each LTERM has a fixed relationship with a physical terminal.