There are two modes available, INCLUDE mode and EXCLUDE mode. You can specify the MODE by including one or more MODE control statements in the GVBDBFON or GVBREFR SYSIN stream. Also, there is a SYSTEM default mode available through the DEFAULTMODE system constraint.
Once you specify a particular mode, that mode remains in effect until you specify another mode card in the control stream (see the sample GVBDBFON and GVBREFR SYSIN streams in Chapter 5, "Batch Utility Programs").
The MODE is specified simply as MODE=INCLUDE or MODE=EXCLUDE. Each LEVEL selector belongs to the MODE control statement that precedes it, or the system default mode if there is no MODE established prior to the level selector. All LEVEL selectors that follow a MODE control up to the next MODE control (or the end of file) are called a mode control group. The mode control group is an INCLUDE mode control group, if the owning mode card specifies INCLUDE; otherwise the group is an EXCLUDE mode control group.
At VSAM OPEN time, the intercept routine compares the cluster name, SMS class name(s), job name, program name, and the program/dd name combinations of the OPEN issuer against a table that was built from your control statements at initialization time, or modified at refresh time. If a matching LEVEL SELECTOR is found in any EXCLUDE mode control group, this OPEN is not dynamically buffered. The OPEN intercept routine passes control directly to normal VSAM OPEN. Any constraints associated with an excluded level selector are ignored.
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