gtpc1m1o | Transmission Control Protocol/Internet Protocol |
The OSA read buffers are used to transfer data to the TPF system from an OSA-Express connection. Each OSA-Express connection has its own set of read buffers allocated in main storage.
The OSABUFF parameter on the SNAKEY macro in CTK2 defines the number of 64-KB read buffers assigned for each OSA-Express connection. You can specify a value of 16, 32, or 64 for the OSABUFF parameter. See TPF ACF/SNA Network Generation for more information about the SNAKEY macro.
The amount of storage required for each valid OSABUFF value is as
follows:
Number of OSA Read Buffers (OSABUFF) | Storage Required |
16 | 1 MB × MAXOSA parameter value |
32 | 2 MB × MAXOSA parameter value |
64 | 4 MB × MAXOSA parameter value |
Consider the following when determining how many OSA read buffers to define:
Increasing the OSABUFF parameter is only necessary for systems with significant message rates. In a low-volume TPF system, the default of 16 buffers should be enough. However, in a high-volume production system (for example, a system that receives more than 2000 messages per second), it is best to increase the number of buffers.
The message rate at which you decide to increase the number of buffers can vary based on processor speed, number of I-streams, and the environment in which the TPF system is running. One way to determine whether you need to increase the number of buffers is to look at the number of messages that are received out of order. If the percentage of messages received out of order increases as the message rate increases, it can be an indication that the buffers currently available to the OSA are being filled and the value of the OSABUFF parameter should be increased.