Symbol resolution tables

This constant specifies the number of queue pointers in every SRT directory for networks other than this VTAM® network (that is, all networks with a network ID other than the network ID of this VTAM specified on the BUILD and NETWORK macroinstructions that are included in the NCP definition program). The IBM-supplied default value is 43. You can change the number of SRT entry queues in each directory by specifying a number in the range 0–32767 (X'7FFF'). If you specify 0, VTAM uses the default value of 43. Using a prime number of queue pointers results in a fairly even distribution of SRT entries to the queues. It is advisable that you choose a prime number.

Note: For networks with a large number of LUs, increasing this number shortens the length of the queues, thereby decreasing the logon time.

See the following instructions and information before changing the default directory size. To estimate the number of entries in the other network's symbol resolution table (SRT), add the following:

Class-of-service table
- Add one SRT entry for each COS table associated with another network by COSTA operands in active gateway NCPs. That is, add one to your count of SRT entries for every COSTAB operand specified on the BUILD and NETWORK macroinstructions with network IDs other than that of this host.
Adjacent SSCP table
- Add one SRT entry for each destination SSCP in another network that is specified in an active adjacent SSCP table.
- Add one SRT entry for each default adjacent SSCP list for the other networks.
Network address
- Add one SRT entry for the real network address of each cross-network resource that establishes a session through this VTAM SSCP.
- Add one SRT entry for the alias network address of each host-network resource that establishes a session through the VTAM SSCP.
- Add one SRT entry for each alternate gateway path to other-network SSCPs, if the ADJNETSA operand is specified on the GWPATH statement.
SSCPID
- Add one SRT entry for each other-network SSCP that has a session with this VTAM SSCP.
PCID
Add one SRT entry for each LU-LU session.
Nodes
Add one SRT entry for each active CDRSC in another network.

Divide the number of entries in the other network's symbol resolution table by two times the size of the other network symbol resolution table, OSRTSIZE, to obtain an average SRT queue depth. Performance increases as the SRT queue depth decreases. Therefore the larger the size of the SRT table, the better the performance.

Making the table larger can improve in two ways:

The search is shorter and saves on CPU cycles.
The page each element references is easily accessed, so there is less paging with the larger table size.