It might be necessary to cancel VTAM® if VTAM cannot be halted in any other way. VTAM should be canceled only if the HALT and HALT QUICK commands do not work properly. Canceling VTAM causes the immediate abnormal termination of VTAM without an orderly shutdown of the domain.

The HALT CANCEL command cancels VTAM. This command depends only on the proper functioning of the abnormal termination facilities on the host operating system. The HALT CANCEL command causes an abnormal termination with a system completion code of X'0A9'. When VTAM is canceled, no further I/O operations occur. Application programs using VTAM are notified of a VTAM shutdown through their TPEND exit routines, if possible. Data being transmitted on sessions might be lost. If TPEND cannot be scheduled for an application program, the application program is also abnormally terminated, if possible. In some circumstances, you might have to cancel some application programs.