SYSUT1 in ACF2 proc and GSO BACKUP record

Products

• ACF2 - z/OS

Issue/Introduction

SYSUT1 in ACF2 proc and the GSO BACKUP record

Environment

Release : 16.0

Component : ACF2 for z/OS

Resolution

The backup work file SYSUT1, can be specified in:

- The ACF2 proc to be allocated at CA-ACF2 startup 

- Can be dynamically allocated when BACKUP commences using the PRISPACE, SECSPACE, and WORKVOL/WORKUNIT fields of the BACKUP record. 

Specifying SYSUT1 in the ACF2 PROC overrides the dynamic allocation of SYSUT1 based on the GSO BACKUP record . 

To use the dynamic allocation of files, remove the SYSUT1 statement from the CA-ACF2 startup procedure to prevent the override of the GSO BACKUP record and BACKUP record can be changed as shown below for required allocations:

SET CONTROL(GSO)
CHANGE BACKUP PRISPACE(x) SECSPACE(x)

To determine how much space in Cylinders is actually needed for SYSUT1,  run IDCAMS LISTCAT on ACF2 databases, look at the record size for largest database and add around 10% more allocation to be on the safe side.

There is another option to change the GSO BACKUP record SYSUT1|NOSYSUT1 to NOSYSUT1, which will cause the copy to the interim SYSUT1 file to be bypassed.

Normally the VSAM file is first copied to the SYSUT1 file before being copied to the backup file. It is an interim temporary file where the data is copied there first before it is copied to the backup sequential datasets.

This was done in the past(decades ago)  just in case there is a problem in the backup, however with the hardware and software advances today it is really not necessary. .

The best practice recommendation is to use NOSYSUT1 in BACKUP record which will bypass the interim SYSUT1 processing as shown below:

SET CONTROL(GSO)
CHANGE BACKUP NOSYSUT1