Any services in SAS that use TK memory can greatly benefit by tuning the values used for each of these environment variables. The values that work best for a specific server or service within SAS can vary based on how that server uses TK memory.

Note: The values used in the environment variables shown below are set for illustration purposes. At your installation, set the variables according to what is optimal for each server that will be running under z/OS.

set TKOPT_MEMLEAVE=1048576

This setting is expressed in bytes and should be the same as MEMLEAVE= option. This option is used to reserve a certain amount of memory from the address space that might be needed for various system tasks. You must convert the MEMLEAVE option setting to bytes. For example:

• If the MEMLEAVE setting is 512K, the TKOPT_MEMLEAVE setting = 512*1024.
• If the MEMLEAVE setting is 1M, the TKOPT_MEMLEAVE setting = 1*1024*1024.

set TKOPT_OVFL_FIXED=3

This setting enables a multiplier value for fixed cell-pool allocation requests. This setting causes overflow segments of 4K, 12K, 512K, or 1MB, depending on the fixed cell-pool size. Default values for fixed pools vary according to the fixed cell size.

set TKOPT_OVFL_SMALL=5

This setting enables a multiplier value for small cell-pool allocation requests (less than 256 bytes). This setting causes overflow segments of "n" times larger than the default. The default value for small cell pools causes overflow in segments of 4K.

set TKOPT_OVFL_MEDIUM=6

This setting enables a multiplier value for medium cell-pool allocation requests (less than 2,296 bytes). This setting causes overflow segments of "n" times larger than the default. The default value for medium cell pools causes overflow in segments of 8K.

set TKOPT_OVFL_LARGE=20

This setting enables a multiplier value for large cell-pool allocation requests (less than 17,913 bytes). This setting causes overflow segments of "n" times larger than the default. The default value for large cell pools causes an overflow cell count of 10.

Note: Large cell pools are used only when the TKOPT_CPOOL3 variable is specified. TKOPT_OVFL_LARGE has no effect in the absence of TKOPT_CPOOL3.

set TKOPT_CPOOL3=

This is a Boolean variable that tunes memory management for the metadata server. Specify this environment variable as shown above (without a value).

Refer to SAS Note 31661 for an enhancement to the TKOPT_CPOOL3= environment variable.

Refer to SAS Note 31147 for an enhancement that can be implemented for SAS^® OLAP Server.

Operating System and Release Information

Product Family	Product	System	SAS Release
			Reported	Fixed*
SAS System	Base SAS	z/OS	9.1 TS1M3

* For software releases that are not yet generally available, the Fixed Release is the software release in which the problem is planned to be fixed.

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Environment variables to use for tuning servers under the z/OS system. Settings for these environment variables are very dependant on the server and should be tuned for that specific server environment.

Type:	Usage Note
Priority:

Date Modified:	2008-04-10 14:14:16
Date Created:	2008-04-01 16:09:37