VTAM uses buffer pools to control the handling of data: VTAM control blocks, I/O buffers, and channel programs that control the transmission of data. Each buffer pool handles storage for a different VTAM service, therefore, the needs of your network determine which buffer pools are used the most. After you determine which buffer pools are the most important to your system, you may want to change the size of some of them.
When you set a buffer pool size, you are reserving storage for use only by that buffer pool. If you specify buffer pools that are larger than necessary, you are setting aside storage that is not being used. In effect, the storage is being wasted when it could be used in other areas.
When you set a buffer pool size that is too small, VTAM reaches buffer pool limit and dynamically allocates more space in the buffer pool. When the current need is satisfied, VTAM dynamically de-allocates space in the buffer pool. Specifying small buffer pools conserves storage, but causes frequent CPU use for expansion and contraction.
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