ZHYPERLINK

Use the ZHYPERLINK statement to enable, disable the zHyperlink facility. If no ZHYPERLINK statement is specified, the zHyperlink facility is disabled on the system by default. The ZHYPERLINK keyword may be abbreviated as ZHL.

ZHYPERLINK OPER=ALL|READ|WRITE|NONE,READLIMIT=n]

ZHL OPER=ALL|READ|WRITE|NONE,READLIMIT=n]

Specifies whether the zHyperlink facility is enabled on a system for all I/O operations, only read I/O operations, only write I/O operations, or disabled for all I/O operations.

,READLIMIT=n]

n indicates the read data limit, expressed in KB. For example, when 4 is specified, the read data limit is 4 K + 32 (32 bytes is always added to the specified limit). The valid range is 0 to 32.

If no value is specified or 0 is specified, the system uses the default for the detected zHyperLink capability. When original zHyperLink capability is detected, regardless of what is specified, the read data limit remains at 4 K + 32. When zHyperLink Acceleration is detected, the default read data limit is 16 K + 32.

This value is made available to access methods that use ZHYPERLINK. It is up to the access method to use this data limit when determining whether I/Os are candidates for ZHYPERLINK read attempts. For example, IBM Media Manager may be used to read a VSAM dataset with CI size of 8 K. IBM Media Manager would use the read limit that is in effect for one or more devices that contain the VSAM dataset and decides whether ZHYPERLINK read operations can be used. For more information about ZHYPERLINK I/O operations, see zHyperLink I/O in z/OS DFSMS Using Data Sets and Defining use of zHyperlinks in z/OS DFSMSdfp Storage Administration.

Default: NONE