SQA/CSA thresholds
Ensuring the appropriate size of the extended SQA and extended CSA storage is critical to the long-term operation of the system.
If the size allocated for SQA is too large, the thresholds for the IRA100E and IRA101E messages will not be met and CSA can become exhausted and cause a system outage. One way to avoid this problem is to allocate the minimum SQA required or allow for some CSA conversion so that the storage thresholds that trigger the IRA100E and IRA101E messages are based only on the remaining CSA.
If the size allocated for extended SQA is too small or is used up very quickly, the system attempts to use extended CSA. When both extended SQA and extended CSA are used up, the system allocates space from SQA and CSA below 16 megabytes. The allocation of this storage could eventually lead to a system failure.
- When the size, in bytes, of combined total of free SQA + CSA pages falls below the "high insufficient" threshold, the system issues message IRA100E
- If the size, in bytes, of available SQA and SQA pages falls below the "low insufficient" threshold, the system issues message IRA101E
- If storage is freed such that the available SQA+CSA amount reaches the "high sufficient" threshold, the system issues message IRA102I
- There has been storage growth beyond the previous normal range.
- Allocation of SQA and/or CSA is inadequate.
- The current thresholds at which the IRA100E and/or IRA101E messages are issued are too high for your installation.
Offset | Default Value | System Enforced Minimum | Description | Comments |
---|---|---|---|---|
0000 | x'41000' | x'9000' | Sufficient space high | IRA102I message issued at this threshold |
0004 | x'21000' | x'5000' | Sufficient space low | IRA102I message issued at this threshold |
0008 | x'40000' | x'8000' | Insufficent space high | IRA100E message issued at this threshold |
000C | x'20000' | x'4000' | Insufficient space low | IRA101E message issued at this threshold |
If you change the default thresholds, make sure that the new sufficient threshold values are at least x'1000' larger than the insufficient values. The new values become effective at the next IPL.