Use TUNE=OLD option to prevent balancing resources for concurrent sort applications

Description

Beginning with z/OS V2R1, a new TUNE installation default allows you to specify whether DFSORT should allocate storage in increments with additional disk work space to minimize the risk of failure, or to allocate all storage at initialization so disk work space allocation can be reduced. The IBM-supplied default for the new TUNE installation option is TUNE=STOR which specifies allocation of available central storage as needed in increments sized to balance resource usage for concurrent sorts. If you want DFSORT to allocate available central storage using fixed sized increments, as in previous releases, you can set TUNE=OLD.

TUNE has the following values:

STOR
DISK
DDYN
OLD

Table 1 provides more details about this migration action. Use this information to plan your changes to the system.

Table 1. Information about this migration action
Element or feature:	DFSORT.
When change was introduced:	z/OS V2R1.
Applies to migration from:	z/OS V1R13.
Timing:	Before the first IPL of z/OS V2R2.
Is the migration action required?	Yes, if the default value TUNE=STOR is not acceptable.
Target system hardware requirements:	None.
Target system software requirements:	None.
Other system (coexistence or fallback) requirements:	ICEPRMxx member(s) of PARMLIB can be shared between systems running different releases of DFSORT. Any installation options specified in the ICEPRMxx member that are only supported in the newer release of DFSORT will be ignored on the system using the earlier release of DFSORT.
Restrictions:	None.
System impacts:	None.
Related IBM® Health Checker for z/OS® check:	None.

Steps to take

Follow these steps:

Use ICEPRMxx members activated by a START ICEOPT started task command to set the TUNE=OLD option, as appropriate.
Alternatively, you can set TUNE=OLD with the previous (less preferred) method of using the ICEMAC macro and usermods.

Reference information

For more information about the TUNE installation option, see z/OS DFSORT Installation and Customization.