DFHFCDN (file control DSN block manager)

Call mechanism

Kernel subroutine call. Automatic stack storage acquired as part of the call.

Entry address

DFHFCDN. The entry point address is held in FC static storage in a field named FC_FCDN_ADDRESS, which is set by DFHFCRP when it loads DFHFCDN.

Purpose

The DSNAME block manager is part of the file control component. This program is called to perform various operations on data set name blocks. These operations include connecting and disconnecting DSN blocks and FCT entries, setting their attributes, and deleting them when no longer required. The program also allows the caller to inspect a particular DSN block or browse a set of blocks. It can also be called to update the backup while open (BWO) attributes in the ICF catalog for VSAM data sets, and to set the quiesce state to normal in all DSN blocks. Finally it can be called to catalog the information in a DSN block to the CICS global catalog.

Called by

DFHAMFC

Connect a DSN block to a newly created FCT entry

DFHAMPFI

Connect the DSN block for the CSD to the associated FCT entry

DFHEIQDN

Connect, disconnect, delete, set attributes, browse, and inquire against DSN blocks in response to external requests; and to update the BWO attributes in the ICF catalog for a VSAM data set to a ‘forward recovered’ state

DFHEIQDS

Connect or disconnect DSN blocks and FCT entries in response to external requests

DFHFCLF

Set the availability attribute to unavailable after a forward recovery log stream failure

DFHFCMT

Disconnect the DSN block when deleting an FCT entry

DFHFCN

Connect or disconnect and to catalog a DSN block

DFHFCRC

Update the recovery point in the ICF catalog for all VSAM data sets that are open for update in non-RLS mode and defined as eligible for BWO support at keypoint time

DFHFCRD

To reset all quiesce states to normal after an SMSVSAM server failure

DFHFCRO

Connect or disconnect and to catalog a DSN block

DFHFCRP

Connect or reconnect DSN blocks during file control initialization or restart.

Inputs

The FCDN parameter list, as defined by the DFHFCDNA DSECT, is created as part of the subroutine call.

Outputs

Output parameters, as part of the FCDN parameter list. Apart from the response, all these are returned on the inquire or browse requests. The parameters include:

Operation

• Connect:

  The inputs are a data set name and an FCTE pointer or an FCTE token, with an indication of whether the entity to be connected is a base or an object.

  If the FCT entry is already connected, the connection is broken before connecting it to a DSN block representing the new object. The DSN block that is connected can exist already, or DFHFCDN creates a new block before connecting it.

  The request is rejected if it requires an existing connection to be broken, and there are uncommitted updates to the file; that is, there are retained locks.

• Disconnect:

  The connection between the FCT entry and the DSN block is broken. The DSN block remains even if there are no other FCT entries connected to it. The request is rejected if there are uncommitted updates to the file: that is, there are retained locks.

• Delete:

  Checks are made to ensure that the DSN block is allowed to be deleted. If the deletion can proceed, the table manager is called to delete the DSN from the DSN index, and the storage domain is called to free the storage.

• Inquire:

  The attributes stored in the DSN block are returned to the caller in the FCDN parameter list.

• Set:

  The availability status is set in the DSN block. The catalog domain is called to catalog the change.

• Start browse, get next, end browse:

  The DSN blocks are browsed in order. For each, the attributes are returned to the caller.

• Catalog:

  The information in a DSN block is cataloged to the CICS global catalog.

• SET_CATALOG_RECOVERED:

  This function is used by DFHEIQDN. DFHFCDN in turn issues a SET_CATALOG_RECOVERED call to DFHFCAT to update the BWO attributes in the ICF catalog for a given VSAM data set to a ‘forward recovered' state.

• UPDATE_RECOVERY_POINTS:

  This function is used by DFHFCRC. DFHFCDN in turn issues a SET_CATALOG_RECOV_POINT call to DFHFCAT to update the recovery point in the BWO attributes in the ICF catalog for every data set that is open for update in non-RLS mode and defined as eligible for BWO support.

  The recovery point is the time from which a forward-recovery utility should start applying log records. It is always before the time the last backup was taken. For further information about recovery points and backup while open in general, see the Troubleshooting for recovery processing.

• RESET_ALL_QUIESCE_STATUS:

  This function is used by DFHFCRD. The DSNB table is scanned, and the quiesce status is reset to normal in each DSNB.

How loaded

By DFHFCRP as part of file control initialization.