VLFNOTE command

When you change data that is shared across systems and managed by the virtual lookaside facility (VLF), you might need to enter the VLFNOTE command to notify VLF of the change. VLF needs to know when you make changes to the data it manages so that it can make current data available for users. The types of data VLF manages are:

Data in a partitioned data set (PDS) or partitioned data set extended (PDSE)
A named collection of data (non-PDS)

Note: The term partitioned data set (PDS) in the following VLFNOTE description refers to PDS and PDSE data sets.

The type of data and the system environment determine whether you need to enter VLFNOTE.

You do not need to use VLFNOTE (because notification to VLF is automatic) when both of the following are true:

VLF is running on z/OS systems and are part of a single sysplex.
The changed data belongs to a partitioned data set class.

When both conditions are true, VLF receives notification automatically through sysplex services. (z/OS MVS Setting Up a Sysplex describes running VLF in a sysplex.) Otherwise, you need to enter VLFNOTE.

The types of changes that require VLF notification are listed below:

For data in a PDS, enter VLFNOTE when you are:

Adding a member to an eligible data set (a data set that is identified to VLF).
Adding a member to a non-eligible data set when both of the following are true:
- The new member is in a user's SYSPROC concatenation ahead of an eligible data set.
- The eligible data set has a member with the same name as the new member.
Updating an existing member of an eligible data set.
Deleting an eligible data set or member of an eligible data set.

To notify VLF about changes to data in a PDS, use the VLFNOTE command syntax described in Changing data associated with a partitioned data set.

For non-PDS data, use VLFNOTE when you are:

Adding a minor name to a major name.
Updating a minor name associated with a major name.
Deleting a minor name from a major name.

To notify VLF about changes to non-partitioned data, use the VLFNOTE command syntax described in Changing non-PDS data.

There are several ways to issue the VLFNOTE command. Depending on the method available at your installation you can:

Logon to each of the other systems in your complex and enter VLFNOTE.
Send a message to a user on each of the other systems in your complex and have them enter VLFNOTE.
Submit a short batch job, with system affinity, to each of the other systems in your complex and issue VLFNOTE in the job.
If your installation is using APPC/MVS, write an APPC/MVS transaction program to prompt the affected systems to issue the VLFNOTE command. Each of the affected systems must have an APPC/MVS transaction program that will issue the VLFNOTE command.

See z/OS MVS Programming: Authorized Assembler Services Guide, for more information about VLF notification.