IBM Mainframe Forum

Posted: **Tue Oct 29, 2013 11:07 am**

VLF :
Virtual Lookaside Facility which is used to retrieve the most currently used objects from Virtual Storage rather than searching in DASD

It is used to improve the performance and my question is

whether it applies only to Load Modules

LLA:
Library Lookaside

Is it a part of VLF ?

and what is LLA and is there any connection between LLA and VLF ?

Posted: **Tue Oct 29, 2013 5:23 pm**

As this topic has NOTHING to do with the Forum Rules or Feedback and Suggestions I ahve moved it to a better place. It may not be the best place but I am not going to decide the best place for you. Same applies to your other post.

Posted: **Tue Oct 29, 2013 5:51 pm**

From the MVS Initialization and Tuning Reference manual in the MVS bookshelf:

21.0 Chapter 21. CSVLLAxx (library lookaside (LLA) list)
Use the CSVLLAxx member to specify which libraries (in addition to the LNKLST concatenation) library lookaside (LLA) is to manage. If you do not supply a CSVLLAxx member, LLA will, by default, manage only the libraries that are accessed through the LNKLST concatenation.

and from the Using CICS manual in the CICS Tranaction Server bookshelf:

Using LLA (MVS library lookaside)

Modules loaded by CICS® from the DFHRPL libraries may be managed by the MVS™ LLA (library lookaside) facility. LLA is designed to minimize disk I/O by keeping load modules in a VLF (virtual lookaside facility) dataspace and keeping a version of the library directory in its own address space.

LLA manages modules (system or application) whose library names you have put in the appropriate CSVLLA member in SYS1.PARMLIB.

So yes, LLA / VLF applies ONLY to load modules (both in PDS and PDSE), and VLF is the dataspace used by LLA.

Posted: **Tue Oct 29, 2013 9:05 pm**

Thanks a lot Robert

Posted: **Wed Oct 30, 2013 9:56 pm**

Try reading
Identifying CLISTs and REXX execs to VLF

z/OS TSO/E Customization
SA22-7783-12

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