HPRPST start option


   .-HPRPST--=--(--8M--,--4M--,--2M--,--1M--)----------------------------------.   
>>-+---------------------------------------------------------------------------+-><
   '-HPRPST--=--(--low_limit--,--med_limit--,--high_limit--,--network_limit--)-'

range:

5 secs - 24 hours (low, medium, high, and network limits)

Specifies the maximum amount of time during which VTAM® attempts to perform a path switch before it ends a connection, when HPR=RTP. The value can be expressed as nS (seconds), nM (minutes), or nH (hours). If you do not specify an S, M, or H, seconds are assumed. When VTAM determines that it is necessary to switch paths for the RTP logical connection, it starts a path switch timer.

You can specify different time limits for low, medium, high, and network transmission priority connections. For example, you might allow only a 20-second (20S) limit for interactive connections to remain open during a path switch, but allow an hour (1H) limit for batch connections to remain open while waiting for restoration of a path that is unavailable as a result of maintenance activities.

Although there are no strict rules for coding HPRPST, consider the following conditions:

An interval that is too short might not allow enough time for a path switch attempt to succeed and find a new route. This could be a problem, particularly when the network is congested.
An interval that is too long might use up storage and could leave an LU in a state in which other LUs or applications cannot communicate with it.
Set the network transmission priority to a substantially lower value than the other transmission priorities. This allows CP-CP sessions (which carry signals that flow at network priority) to complete a path switch before the path-switch timer for an RTP connection carrying an LU-LU session expires.
When specifying the HPRPST value, take into consideration HPRPSDLY, which allows you to set a path switch delay.
- The HPRPSDLY start option affects all RTP pipes with endpoints on the host where it is specified.
- For RTP pipes that are directly attached to Enterprise Extender, also take into consideration the EE-only path switch delay values that can be specified for individual EE connections with the HPRPSDLY operand. Consider coding the HPRPSDLY operand value EEDELAY for these connections. When you specify the EEDELAY value, and EE is the only path to the RTP partner, specify the HPRPST value to be sufficiently large to enable the EE connection to be re-established. A sufficiently large value enables the RTP pipe and its associated LU-LU sessions to be successfully recovered. The HPRPSDLY operand is available on the following major nodes:
  - For predefined EE connections, define this parameter on the PU definition in the switched major node.
  - For EE connection networks, define this parameter on the connection network GROUP definition statements in the EE XCA major node.
  - For dial-in EE connections that have associated PUs that are dynamically created, define this parameter on the model major node (DYNTYPE=EE) PU definition statement.
Although HPR connections that are established for some sessions with multinode persistent session (MNPS) applications might have a network transmission priority, these connections use the HPRPST value that is specified for the high transmission priority limit. See z/OS Communications Server: SNA Network Implementation Guide for more information about recovering MNPS sessions.

You can change the value of HPRPST with the MODIFY VTAMOPTS command while VTAM is running. The new HPRPST values do not affect existing RTP connections, but are used for any new RTP connections that are activated.