The forwarding of events to the various ILCS instances is controlled by activating or deactivating the appropriate PCDs.
A distinction is made here between instance-specific and task-specific events and contingencies.
If no precautionary measures are taken, the subsystem is informed of program errors (STXIT class PROCHK and ERROR) even if the error did not occur in the subsystem.
If the application contains several components with private ILCS instances, behavior in the event of an error is influenced by the order of the SEH logons to the operating system, something which is normally not desired.
If the subsystem may ignore all events, the SEH should be deactivated with IT0SEHEN. This does however have the disadvantage of also deactivating the error handling of the language runtime system.