Issuing the DSLIST command consumes a lot of VLF

Products

• SYSVIEW Performance Management

Issue/Introduction

After upgrading z/OS from z/OS V2.1 to V2.3, issuing the DSLIST command suddenly caused VLF to use a large amount of memory.
Has the DSLIST specification changed? Also, is there a way to solve it?

Resolution

There is no change in the specifications of the DSLIST command for z/OS v2.1 and v2.3.
As a workaround, prevent this command from being issued in CAPTURE.
Or, consider using this command after specifying OPTIONS NOUSEBLK.

<Reference>
DSLIST calls IARQDSPD (IBM's page status interface routine) for each page in the data space to collect information about the pages in the data space (if UseBlk is set).
(IBM's page status interface routine) for each page in the data space to gather information about the pages in the data space.
If the return code of this IARQDSPD is 0xC (the status of the page is not determined), the page may be loaded into real storage because it references that page.
This will lead to an increase in real storage in the VLF address space.