IOS_CAPTUCB_PROTECT

Description:

This check verifies that captured UCB protection is active on the system. Captured UCB protection is suggested.

Reason for check:

UCBs (Unit Control Blocks) are control blocks in storage that define the characteristics of devices. Legacy software may require a subset of these to reside in the first 16 megabytes of storage. To accommodate 24-bit addressability there is a service to capture the UCB and temporarily put the UCB in the 24-bit addressable area. Captured UCB Protection places the UCBs temporarily below the line in write protected storage, so legacy software cannot interfere with the state of the devices. IBM® recommends that Captured UCB Protection is active.

You can verify the state of captured UCB protection using the following console command:

DISPLAY IOS,CAPTUCB

In response to this command, the system issues message IOS088I to display the state of captured UCB protection:

IOS088I 12.12.00 CAPTURED UCB DATA 243    
CAPTURED UCB PROTECTION IS DISABLED

To change the state, see the SETIOS command in z/OS MVS System Commands.

z/OS® releases the check applies to:

z/OS V1R12 and later.

Parameters accepted:

Yes, the following parameters are accepted:

PARM(‘PROTECT(state)')

Since, there may be a rare instance where captured UCB protection should not be enabled, you can set the expected state of captured UCB protection the check expects to either:

PARM('PROTECT(YES)'), which is the default, indicates that the expected captured UCB protection state is enabled.
PARM('PROTECT(NO)') indicates that the expected captured UCB protection state is disabled.

User override of IBM values:

The following shows the default keywords for the check, which you can override on either a POLICY statement in the HZSPRMxx parmlib member or on a MODIFY command. This statement may be copied and modified to override the check defaults:

 UPDATE
        CHECK(IBMIOS,IOS_CAPTUCB_PROTECT )
        INACTIVE
        SEVERITY(MED) INTERVAL(ONETIME) DATE('date_of_the_change')

Debug support:

No.

Verbose support:

No.

Reference:

For more information, see information on the SETIOS command in z/OS MVS System Commands.

Messages:

This check issues the following exception messages:

IOSHC101E

See IOSHC messages in z/OS MVS System Messages, Vol 9 (IGF-IWM).

SECLABEL recommended for MLS users:

SYSLOW