20D

Explanation
An abend occurred in a subtask. The subtask either: Operated in step-must-complete (MC) status
Issued an ABEND macro with the STEP option

 As a result, the system abnormally ended the job step.
Note: The
original abend code is in the TCBCMP field of the task control block
(TCB) for the subtask that caused the error.

System action
The system ends the job step. The system writes
an ABEND dump for the failing job step, if it provides a dump data
set.

Programmer response
Find the original abend code in the TCB
of the subtask that caused the error. Continue diagnosis with that
abend.

Source
Recovery termination manager (RTM)