BSAM, QSAM, and VSAM ESDS access to remote files

BSAM, QSAM, and VSAM ESDS applications can access files stored on remote NFS servers through the NFS client. This will allow existing MVS application programs access to data on other systems using BSAM, QSAM, and VSAM ESDS interfaces. The BSAM, QSAM, and VSAM ESDS access methods assume that all text files are EBCDIC. When using these access methods, the delim parameter indicates whether the remote files contain text or binary data. Text data consists of records that are separated by a delimiter. If the delim parameter is not binary, the EBCDIC text delimiter is used by the access methods when processing the remote files. The delim parameter is supported on the NFS client installation parameter and TSO MOUNT command.

Note: The z/OS NFS client can also access VSAM key-sequenced (KSDS) and relative record (RRDS) data sets.

All the remote file objects under the same mount point have the same delim value. The delim parameter cannot be set on a file basis under the mount point. The delim parameter in the TSO MOUNT command overrides the delim parameter specified in NFS client installation parameter. However, you can override the delim parameter on the TSO MOUNT command with the filedata parameter on a JCL DD statement, SVC 99, or TSO ALLOCATE command. The filedata parameter can be either text or binary.

For BSAM, QSAM, and VSAM ESDS applications accessing files stored on remote NFS servers, the NFS client provides data conversion when the xlat=Y parameter is specified. It uses the cln_ccsid and srv_ccsid settings. When xlat=N, the NFS client will not perform data conversion. The filedata parameter on a JCL DD statement is also used to specify if the data consists of text records separated by delimiters or if the data is binary and does not contain record delimiters. To avoid undesirable data conversions, care should be taken to insure the specification of the xlat and delim parameters are not in conflict with the data type specified by the filedata parameter on a JCL DD statement. The filedata and delim parameters only affect BSAM, QSAM, and VSAM ESDS data access and have no affect on the NFS client data conversion. The NFS client data conversion is only controlled by the xlat parameter. The significance of different filedata and delim combinations are described in the following information.

Note: In each case, ensure the NFS client xlat=Y, cln_ccsid, and srv_ccsid parameter settings are correct for the filedata and delim combination.

FILEDATA=TEXT, delim=notBINARY: Specifies that the data is to be accessed as text. The access method appends a record delimiter on output and expects delimiters on input. The delimiter used is that specified on the delim parameter.
FILEDATA=TEXT, delim=BINARY: Specifies that the data is to be accessed as text. The access method appends a record delimiter on output and expects delimiters on input. The delimiter used is the default of the EBCDIC new line character (x'15') since the delim parameter does not specify a valid text delimiter.
FILEDATA=BINARY, delim=notBINARY: Specifies that the data is to be accessed as binary. The access method does not append record delimiters on output, does not recognize record delimiters on input, and it treats all characters as data on input.
FILEDATA=BINARY, delim=BINARY: Specifies that the data is to be accessed as binary. The access method does not append record delimiters on output, does not recognize record delimiters on input, and it treats all characters as data on input.
FILEDATA=not specified, delim=specified: Means that the data is to be accessed according to the value specified in the delim parameter.
FILEDATA=not specified, delim=not specified: Means that the data is to be accessed as binary. The access method does not append record delimiters on output, does not recognize record delimiters on input, and it treats all characters as data on input.

The NFS client also provides UNIX authentication for security and provides the UNIX client's user ID (UID), group ID (GID), and a list of users GIDs to the remote NFS server for authorization checking. When the remote NFS server is the NFS server, the mvslogin command can be used to provide additional security checking through RACF authentication. MVS application programs which require access to data on remote systems may be required to perform an mvslogin.

For information on BSAM, QSAM, and VSAM ESDS applications access to z/OS UNIX or remote files and their restrictions, refer to z/OS DFSMS Using Data Sets.