The I/O buffer pool manages the storage of all network input/output messages
sent from application programs and across channel connections. All network
traffic passes through this pool, regardless of its destination. This buffer
pool also contains channel programs used to service locally attached devices.
The maximum number of I/O buffers allowed is calculated by VTAM from
the Expansion Limit value specified in IOBUF statement in the VTAM start options
(for example, SYS1.VTAMLST(ATCSTRxx)).
When calculating this limit, VTAM
takes into account how many buffers fit on a page. If XPANLIM is not specified
in buffer definition or is coded 0, buffer expansion is not limited and a
value of 2,147,483,647 is displayed in the field.
This situation is
triggered when Expansion Limit is greater than 90% of its capacity. To address this situation, increase the Expansion Limit value.
This is a critical situation. By default, this situation starts automatically. It should be run
at startup.
Note: Applies to the I/O buffer pool only.
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