Use the START VLF command to start the virtual lookaside facility
(VLF) and the START DLF command to start data lookaside facility (DLF).
VLF is an MVS™ service that enables applications to minimize
I/O operations for frequently retrieved objects. DLF is an MVS service
that provides the capability for multiple jobs to share access to
large data objects in storage. It enables QSAM and VSAM applications
to minimize I/O operations.
VLF and DLF will not start if already active on the system; the
START command will be rejected. Also, they will not start if the parmlib
is not allocated to the appropriate started task; if the specified
parmlib member is not found, or is empty; or if there is no valid
class found in the specified parmlib member.
S {VLF|DLF},SUB=MSTR[,REUSASID=YES][,NN=xx]
|
The parameters are:
- VLF,SUB=MSTR
- Invokes the VLF procedure that starts the virtual lookaside facility
(VLF).
- DLF,SUB=MSTR
- Invokes the DLF procedure that starts DLF.
- REUSASID=YES
- Indicates that a reusable ASID should be assigned to the VLF or
DLF address space.
- NN=xx
- Indicates that the system is to start VLF using the COFVLFxx member
of the logical parmlib or that the system is to start DLF using the
COFDLFxx member of the logical parmlib. In each case, replace xx with
two alphanumeric characters that match the suffix of the parmlib member.
If
you do not identify a parmlib member, VLF uses the COFVLF00 default
parmlib member and DLF uses the COFDLF00 default parmlib member.
See z/OS MVS Initialization and Tuning Reference for
more information about the use of the COFVLFxx or COFDLFxx member.