Linked tables in VTS

A linked table (also known as a remote table) is created when a user issues a command to open a table that is already open in a VTS-TSR by specifying the VTS name in the VTSFIRST or VTSLAST run-time options or by specifying it in the LIB-LIST parameter. When the table is opened from the VTS name specified using any of these methods, the table entry in the local TSR is linked to the existing open table in the VTS-TSR. The table data is not duplicated in the local TSR.

Use of the VTSFIRST or VTSLAST options or the LIB-LIST parameter to access a table in a VTS-TSR (linked table) does not allow for update commands against the table. Updates to the table can only be achieved by using the VTS name in the TB-SUBSYSTEM field of the TB-PARM parameter to access the table.

A linked table is always treated as opened for read, even if the table in the VTS-TSR is opened for write. An attempt to open for write a linked table will fail with error code 13-5. A linked table can be identified by the use of an LT or GD command.

If all tableBASE calls in your application are to a VTS-TSR, then using the VTS name in the TB-SUBSYSTEM field of the TB-PARM parameter to access the VTS-TSR is more efficient than using VTSFIRST, VTSLAST or LIB-LIST. Use of the VTS name in the TBPARM completely bypasses the use of the local TSR.

Limitations

The use of linked tables has limitations. Most significantly, if you open a linked table within your local TSR, there will be no indication to you when the actual table is changed, deleted or replaced.