You are responsible for ensuring write integrity if a data set is opened with cross-region SHAREOPTIONS 3 or 4.

When an application program issues a "direct" or "skip-sequential" PUT-for-update or no-update, (RPL OPTCD=DIR|SKP), the updated control interval is written to direct access storage when you obtain control following a synchronous request (RPL OPTCD=SYN) or following the CHECK macro from an asynchronous request (RPL OPTCD=ASY). To force direct access I/O for a sequential PUT (RPL OPTCD=SEQ), the application program must issue an ENDREQ or MRKBFR TYPE=OUT.

Whenever an ENDREQ is issued, the return code in register 15 should be checked to determine if there is an error. If there is an error, normal check processing should be performed to complete the request.

The considerations that apply to read integrity also apply to write integrity. The serialization for read could be done as a shared ENQ and for write as an exclusive ENQ. You must ensure that all I/O is performed to DASD before dropping the serialization mechanism (usually the DEQ).