Restriction: The FIX constraint is effective only if specified for an OPEN that uses LSR buffering. Since CA Hyper-Buf attempts to use LSR processing for random access OPENs as a default, this parameter cannot be validated for applicability by GVBDBFON or the ACTIVATE function (ISPF). No error message is generated, but if FIX is specified for a cluster that does not use LSR buffering, FIX is ignored.
Default: UNFIX
The FIX constraint allows you to page fix VSAM LSR buffers and IOBs. This specification eliminates page faults during VSAM processing and may improve performance.
This option may also degrade performance in a severely storage constrained environment. If your system is already thrashing, do not use the FIX option, as this commits even more real storage.
FIX is the default for buffers that are backed in expanded storage (HIPERSPACE constraint specified) if the address space is also non-swappable (SWAP not specified). See the HIPERSPACE constraint description in the section HIPERSPACE: Backing LSR Buffers in HIPERSPACE for further information.
There are no operands for FIX. You can find an example of the FIX constraint in the section UNFIX: Keeping LSR Buffers and IOBs Pageable.
See the section UNFIX: Keeping LSR Buffers and IOBs Pageable for more information about the UNFIX parameter.
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