Determining and Changing the Size of the *SPOOL Pool

Resolving The Problem

This document provides information on checking and changing the size of the *SPOOL pool to improve the performance of printing through PC5250 printer sessions, Remote Output Queues, *LAN 3812 device descriptions, *LAN IPDS device descriptions, Infoprint Server, and to twinax attached printers.

This document was last updated on 16 September 2014.

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The amount of memory allocated to the *SPOOL pool and the maximum number of active jobs can have an affect on whether a writer is able to print or how quickly a writer is able to print. To determine and change the size of the *SPOOL pool, do the following:

1.	Use the Work with System Status (WRKSYSSTS) command and press the F11 key twice to display the pool data, including the pool names. Note both the Pool Size and the Max Active settings for the *SPOOL pool. Starting in V4R5 IBM OS/400, the pool size is specified in megabytes (M). Prior to the V4R5 operating system, the pool size was specified in kilobytes (KB).
2.	Look at the *SPOOL pool and estimate if it is an acceptable size for the system's printing needs. Refer to the Pool Configuration information in the Work Management Guide (SC41-4306) for a list of the suggested values. When using Remote Output Queue printing, in most cases, Host Print Transform is also being used; Host Print Transform increases the requirement for the *SPOOL pool. A good starting value for the *SPOOL pool is 5000K. The IBM AS/400 Printing V IBM Redbooks recommends a minimum of 6 MB. If the system has many, many writers, this should be higher. Contact the Work Management or Performance queue for additional help, if needed.
3.	Use the following Display System Value (DSPSYSVAL) command to display the current setting of the QPFRADJ (Performance adjustment) system value: DSPSYSVAL SYSVAL(QPFRADJ)
4.	If the QPFRADJ (Performance adjustment) system value is set to 0 (No adjustment), then proceed to the next step to set the size of the *SPOOL pool. If the QPFRADJ system value is set to 1 (Adjustment at IPL), 2 (Adjustment at IPL and automatic adjustment), or 3 (Automatic adjustment), then use the Work with Shared Storage Pools (WRKSHRPOOL) command to first set a minimum percentage for the *SPOOL pool.
5.	To change the size of the *SPOOL pool, use the WRKSYSSTS command and press the F11 key twice, as was done in Step 1 above. Type over the existing values for the Pool Size and Max Active settings and press the Enter key to change the settings. Any additional memory allocated to the *SPOOL pool will be taken from the *BASE pool. Note: If the minimum percentage for the *SPOOL pool is not increased and Performance Adjustment is used, then the pool size will gradually be reduced by Performance Adjustment until it matches the minimum percentage, at which time it will no longer be at an acceptable size for the system's printing needs. For further assistance with adjusting the system's performance, contact a Technical Support representative in the Performance (PERF) queue.

Issues with Performance Adjustment at IPL

Having the QPFRADJ (Performance adjustment) system value set to 1 (Adjustment at IPL) or 2 (Adjustment at IPL and automatic adjustment) when the IBM i system is IPLed can cause shared pools, such as the *SPOOL pool, to be set to a very small pool size.

When the QPFRADJ system value is set to 1 or 2 and the IBM i system is IPLed, the QPFRADJ job allocates nearly all of the system memory to the *MACHINE and *BASE pools before the QSPL and other subsystems are active. Then, when those subsystems are started, they do not have enough memory allocated to perform properly. This can result in the QSPL subsystem having high CPU usage, high faulting, high disk activity, as well as slow printing or the inability to print, following an IPL since there is not enough memory being allocated to the *SPOOL pool for the writer jobs running under the QSPL subsystem.

If experiencing this issue, do the following:

1.	If this issue is seen when the QPFRADJ system value is set to 1 (Adjustment at IPL), try setting this system value to 0 (No adjustment).
2.	If this issue is seen when the QPFRADJ system value is set to 2 (Adjustment at IPL and automatic adjustment), try setting this system value to 3 (Automatic adjustment).
3.	Verify that the pool size and max active are acceptable for the system's printing needs.
4.	Shortly after the next IPL, run the Work with System Status (WRKSYSSTS) command , press the F11 key twice to display the pool data, and check the size of the *SPOOL pool. If set to a very small pool size, such as 0.34MB, manually enter an acceptable pool size and press the Enter key.
5.	Use the Work with Writers (WRKWTR) command and verify that spooled files are printing successfully, and that spool performance is acceptable.