Abstract: System for logging diagnostic information, for use in a transactional environment having means for sending a transactional and re-sendable request to an application program. A counter is associated with the request, wherein a value associated with the counter is updated when an error occurs in the environment. The environment also comprises a counter threshold. The system comprises a comparator, responsive to sending the request, for comparing the value associated with the counter against the counter threshold; a tracing control component, responsive to the value associated with the counter meeting the counter threshold, for enabling a tracing program; and a logging component, responsive to re-sending the request, for logging diagnostic information generated by the tracing program.