STAT.QUEUE.ELEMENTS = statistics record queue size
This parameter specifies the size of the queue that holds statistic records to be written.
The range of the STAT.QUEUE.ELEMENTS initialization parameter is 1-9999 elements, with a default value of 1500. A queue that is too small can degrade system performance, whereas a queue that is too large can cause wasteful storage allocation above the 16 megabyte line. In a Connect:Direct Plex environment, the queue element number is calculated by taking the CDPLEX.MAXSERVER value, adding 1 (for the manager) and then multiplying it by the STAT.QUEUE.ELEMENTS value. If this is less than 5000, then 5000 is used. If greater than 10000, then 10000 is used.
When a IBM® Connect:Direct® task writes a statistic record, it queues the record to be written to the statistics facility asynchronously. The statistics facility then processes the queue and writes the statistics record. This parameter controls the size of this queue. When the queue becomes full, tasks that write a statistics record are held until a slot in the queue becomes available.
You should choose the size of the queue based on how busy IBM Connect:Direct is expected to be during peak-use periods. A lightly loaded system (up to 5 Processes executing concurrently) can run with a small queue, so a queue size of 100 elements may be adequate. However, busier systems require a larger queue (200-1500 elements) to avoid performance degradation caused by queue contention.
There are two size considerations for the statistics queue, the total size and the threshold size. The total size is initially specified by the value of the STAT.QUEUE.ELEMENTS initialization parameter, and can be adjusted if necessary. Each stat queue element takes up 2 KB of space and is allocated above the 16 megabyte line. The threshold size is a value smaller than the total size, and represents a portion of the queue that is reserved for peak-use periods. This helps to improve queue availability under a high workload. The threshold size is calculated automatically, and is usually one-fourth the total size. If the threshold size is inadequate, the total queue size should be increased.
Modifiable through MODIFY INITPARMS command: NO