C03

Explanation
A task tried to end normally by issuing a RETURN
macro or by branching to the return address in register 14. The task
was not ready to end processing because the task had opened one or
more data sets that had not been closed.
The system received
a nonzero return code from Data Facility Product (DFP) indicating
one of the following: DFP returned a nonzero return code.
DFP could not successfully close one or more data sets still open
because a previous error or abend had been ignored by a recovery routine
or a data control block (DCB) abend exit routine.
DFP could not successfully close one or more of the task's data
sets that was still open because the DCB for the data set had been
incorrectly modified. Examples of how the DCB could be incorrectly
modified are: A program containing an open DCB issued an XCTL(X) macro.
A program freed virtual storage that contained an open DCB.
The program modified the DCB incorrectly.

System action
The system may issue message IEC999I. Message
IEC999I provides the address of the DEB that could not be properly
closed.

Operator response
If the application or system programmer asks
for an SVC dump, set the following SLIP trap: SLIP SET,COMP=C03,ACTION=SVCD,END

System programmer response
If the module is an IBM® program, search problem reporting data bases
for a fix for the problem. If no fix exists, contact the IBM Support Center. Provide the dump.

Programmer response
Do the following: If a dump is not produced with the abend, ask the operator
to set a SLIP trap to obtain an SVC dump.
From the dump, find the data extent block (DEB) from
the IEC999I message.  The DEB + X'18' points to the associated
DCB or ACB.
If the DCB or ACB has been freed, then this is a user error.

This is a common user error during subtask processing.
A user must close a DCB or ACB before freeing the storage where the
DCB or ACB resides.  If the DCB or ACB has been overlaid, you must
determine the cause of the overlay.

Source
Recovery termination manager (RTM)