Linked tables and TB-PARM

If every tableBASE call in your applications is to a VTS-TSR, then using the VTSNAME in the TB-SUBSYSTEM field in the TB-PARM to access VTS-TSR is more efficient than using the VTSFIRST, VTSLAST or using the ML command. Use of the VTSNAME in the TBPARM completely bypasses the use of the local TSR.

If you are using VTSFIRST, VTSLAST or ML to add a VTS-TSR to the LIB-LIST, the transaction process will first go to the local TSR (through CICS, IMS or batch) to find a handle (pivot entry) for the table requested, and if it is the first request for that table, a dummy entry will be entered in the local TSR. Then the process will go to the VTS-TSR to locate the table entry. The table entry address in the VTS-TSR would then be used to update the initial dummy entry in the local TSR. On subsequent passes, the local TSR would have a valid address as a pointer to the VTS-TSR for that table. This process describes a linked table. For more information, see the tableBASE Release Notes. Also see Glossary and Linked tables.

Use of VTSFIRST, VTSLAST or using the ML to command to access a table in VTS-TSR (linked table) does not allow for update commands against the table. Updates of the table can only be achieved by the use of the VTSNAME in the TB-PARM to access the table.