Controlling Buffer Limit Size
When a TP sends data to a partner TP on an z/OS system, the data is stored in buffers in the APPC address space until the partner TP receives it. When TPs send large amounts of data and their partners are slow to receive it, more and more buffers of data fill up virtual storage. This situation can cause a shortage of buffer space for other TPs and for the system itself.
- Buffer size control:
This function controls the amount of buffer storage in the APPC address space that is available to all TPs. Use this function to prevent buffer storage from becoming so large that it causes an auxiliary storage shortage when it is paged out, which can cause the system to go into a disabled wait.
- Conversation-level pacing:
This function controls the amount of buffer space that any one conversation can use at a particular time. Use this function when one or more conversations are using so much buffer space that they prevent other conversations from obtaining required buffer space. With conversation-level pacing, APPC/MVS allows data to flow into the buffer at a consistent rate, never allowing the data to exceed the buffer space limit for a conversation. APPC/MVS paces the conversation so it cannot use so much storage that it creates a shortage for other conversations. Pacing controls the rate of transmission of data to prevent overrun or congestion.
The following sections describe several methods that you can use to enable the functions listed above.