ATB004I

Explanation
 An attempt was made to start Advanced Program-to-Program
Communication (APPC) while an APPC address space was already active.

System action
 The system rejects the subsequent START command.
The APPC address space already active continues processing.

Operator response
 If you do not want the existing APPC address
space, cancel it with the CANCEL command. See z/OS MVS System Commands for
more information. 
 Once
APPC has ended (indicated by message ATB002I), a new APPC address
space can be started using the START APPC command.

Module
 ATBINIT

Source
 APPC/MVS

Routing Code
 2

Descriptor Code
 5