Using CA Hyper-Buf › Dynamic Buffering Control Statements › Method of Operation

Method of Operation

Certain types of OPENs cannot be buffered by CA Hyper-Buf. The excluded types of OPENs are:

• LSR/GSR OPENs. These are excluded because the buffers for these types of files are allocated before the ACB is opened. CA Hyper-Buf cannot affect the number of the pre-allocated buffers.

  Note: CA Hyper-Buf can convert NSR requests to LSR, if requested, in which case CA Hyper-Buf does control LSR buffering).

• UBF. These are ACBs that specify user buffering. Since the application controls these buffers, CA Hyper-Buf has no control over the number of buffers allocated.
• Improved Control Interval Access (ICI).
• Control Blocks in Common (CBIC).
• Innovation's IAM type files are bypassed.

After you initialize CA Hyper-Buf, all VSAM OPENs that are not excluded by the above restrictions are screened by the CA Hyper-Buf OPEN intercept routine. This intercept routine compares the cluster name, SMS class names, job name, program name, and program/dd name combinations against the LEVEL selectors that you supplied to CA Hyper-Buf at initialization time. Any constraints attached to any matching level selector are merged into a composite constraint table.

The composite constraint table is built by the OPEN intercept routine. This table is a composite of all of the constraints associated with all matching LEVEL selectors. As each of the LEVELs is checked by the OPEN intercept routine, the constraints associated with each matching level are merged into the composite constraint table.

If no matching LEVEL selectors are found (you did not code any matching CLUSTER, SMSclass, JOB, PROGRAM, or PROGRAM/DDNAME LEVEL selectors), or any constraint not specified in any matching LEVEL selectors (for example, only JOB matched, but you did not specify MAXBUFSP at the JOB level), the corresponding SYSTEM DEFAULT values are used in the composite constraint table.

Note that LEVEL SELECTORS are independent entities. Independent entities mean that a particular level selector is never owned or controlled by any other level selector. The only exception to this rule is the DDNAME selector which is owned by the PROGRAM level selector that precedes it.

After CA Hyper-Buf checks all levels and merges all of the constraints specified at each matching level, CA Hyper-Buf uses the resulting composite constraint table, along with the CI size(s), number of index levels and index set records, and OPEN options (random, sequential, mixed), to determine the optimum number of index and data buffers for this particular OPEN.