Excluded OPENs

An explicitly coded matching EXCLUDE is always honored. For example, if the job name and cluster name are both in an INCLUDE mode control group, but the program name is in an EXCLUDE mode control group, this OPEN is NOT dynamically buffered. Any explicit matching EXCLUDE always takes precedence over all other constraints.

If you specify MODE=EXCLUDE then list several CLUSTER level selectors, all of the clusters named are exempt from dynamic buffering. Normal VSAM buffering is in effect for those clusters and not dynamic buffering. This is true regardless of which job or program might access these clusters.

If there are no matching LEVEL statements found in any INCLUDE or EXCLUDE mode control group at OPEN time, the SYSTEM default mode prevails. The SYSTEM mode is the default mode and is specified by the DEFAULTMODE control statement in the SYSTEM constraints section of the initialization control stream.

Assume that DEFAULTMODE=EXCLUDE is specified in the system defaults and you have several CLUSTER level selectors specified after a MODE=INCLUDE control, but none of the CLUSTERs that were specified matches the cluster currently being opened. This cluster is exempt from dynamic buffering (assuming no matches are found on job or program names). Because no match was found in the INCLUDE mode control groups, the default mode prevails.

The default mode in this case is EXCLUDE, so dynamic buffering is not in effect for this OPEN. The DEFAULTMODE=EXCLUDE does not override explicitly coded LEVEL controls in an include mode control group. Default mode is used only when no matching level selectors are found.

ACCBIAS, a subparameter of the AMP parameter, is used to specify the type of System Managed Buffering used by a file. Because System Managed Buffering is a facility of IBM's System Managed Storage CA Hyper-Buf will not provide dynamic buffering when this parameter is specified. However, you will receive message GVB676I denoting this condition.

If the data set being opened is determined to be controlled by Innovation Data Processing's IAM, message GVB677I is issued and the data set is not processed by CA Hyper-Buf.