A TSO user abend u4039 occurred, and a View task needed to be cancelled.
The most common cause of a IBM Language Environment (LE) U4039 abend is too small a region size.
The U4039 has been issued because the user has set the TERMTHDACT run-time option to request a system dump be generated when an unhandled condition of severity 2 or greater has been encountered. '
If ABTERMENC(RETCODE) is in effect, the application in question continues the termination with an abend code.
If you do not want to see the U4039 abend, there are facilities to suppress it.
See "Abnormal Termination Exit" in z/OS Language Environment Installation and Customization under OS/390 or z/OS Language Environment Customization for ways to suppress or change the U4039 abend.