Issues with security access to transactions and resources can cause transactions to abend.
If a SEP cannot associate the session with the appropriate user when running a transaction, the transaction abends with code AIC0. This can happen before executing a user program at the start of a link level, or during processing of EXEC CICS SIGNOFF.
Impersonation may also cause various abends when transactions try to access resources. Typically, these problems are configuration issues. A user has attempted to access a resource such as a file or a system API for which the log on ID is not authorized.
To resolve these issues, check the access rights of the impersonation users that you use.