PL/I input/output requests

This topic discusses the types of PL/I input/output requests and their restrictions.

A KEYSEARCH parameter value of BEFORE or EQLBFR is not supported by CICS/DDM when accessing a VSAM path. However, these parameter values are supported when accessing a VSAM KSDS.
A POSITION parameter value of PREVIOUS and LAST is not supported when accessing a VSAM path. However, these parameter values are supported when accessing a VSAM KSDS.
Because the DIRECT or SEQUENTIAL KEYED attributes cannot be used to open a VSAM ESDS, it is not possible to access records by relative record number or to have the relative record number returned by using the KEY and KEYTO parameters.
Because VSAM KSDS and VSAM alternate indexes are always defined as a single key field, the NBRKEYFLDS parameter should not be used.

The KEYFROM parameter does not work when writing a record to a VSAM RRDS.
The WRITE request does not work when writing a record to VSAM KSDS that already contains a record with the same key value.
Because the OUTPUT or UPDATE file attribute cannot be used to open a VSAM path, it is not possible to write records to a VSAM path. Instead, the application program must write the record by using the base data set of the VSAM path.

The REWRITE does not work if rewriting a record of a VSAM KSDS when the key value of the record is changed.
Because the UPDATE file attribute cannot be used to open a VSAM path, it is not possible to rewrite records in a VSAM path. Instead, the application program must rewrite the record by using the base data set of the VSAM path.

The DELETE does not work when deleting the record of a VSAM ESDS.
Because the UPDATE file attribute cannot be used to open a VSAM path, it is not possible to delete records in a VSAM path. Instead, the application program must delete the records by using the base data set of the VSAM path. However, if the base data set of the VSAM path is a VSAM ESDS, the DELETE does not work.