Changing the Status of a File
The OPEN, OPEN UPDATE, and CLOSE options allow a DBA to maintain the system at a file level. For example, you use the CLOSE option before you deallocate a file to fix problems associated with it. Within a multi-file area, the OPEN and OPEN UPDATE options let you keep specific files available, while others remain closed. If CA IDMS requires the closed file, it overrides your request as described below.
Note: These functions cannot be performed against native VSAM files using the DCMT VARY FILE command. To accomplish these actions, use the corresponding options of the DCMT VARY AREA command.
DC/UCF Override
If you have not varied the area associated with a file offline, CA IDMS always overrides the file status requested in the DCMT VARY FILE command. For example, if CA IDMS needs to read and write to the file (OPEN UPDATE file status), it overrides your read-only (OPEN file status) request.
Dynamic File Allocation and Deallocation
With the ALLOCATE option, you can bring a new file online without recycling your DC/UCF system. Likewise, the DEALLOCATE option is useful when you need to bring a closed file offline; for example, due to a problem on the disk pack
Forcing Deallocation of Files
The DEALLOCATE FORCE option marks files closed and deallocated without actually closing or deallocating them. This allows you to reallocate the file with a different data set name. You may need to do this, for example, if there is physical damage to the channel. Then, you have to CANCEL the system, because normal shutdown cannot be executed.
Changing the Data Set Name of a File
The ability to change the data set name of a file through a DCMT VARY FILE command is provided for emergency situations only, such as, when a data set is physically damaged and cannot be recovered using its original name. Data set name changes made through a DCMT VARY FILE command are temporary and are not preserved after a normal shutdown. Furthermore, they introduce the potential for incorrect recovery during warmstart unless change tracking is active or appropriate changes are made to the execution JCL of the system to ensure that the correct data set is referenced.
Note: To make permanent changes to the data set name of a file, change its definition in the dictionary and use a DCMT VARY DMCL command to make the change effective within a DC/UCF system.
To change a data set name through a DCMT VARY FILE command, the following conditions must be met:
Changing the Shared Cache for a File
In order to change or remove the shared cache assignment for a file, all shared areas associated with the file must have a status of OFFLINE or TRANSIENT RETRIEVAL
Changing the shared cache for a file affects only the system on which the command is issued. To change the shared cache for all systems that are accessing the file, the command must be issued on each of those systems. In a data sharing environment, the command can be broadcast to all members of the group.
If any area associated with the file is shared, the new shared cache takes effect only if all shared areas associated with the file have a status of OFFLINE or TRANSIENT RETRIEVAL in all group members. This is because the cache name for a file associated with a shared area (other than one in transient retrieval), is determined by the first sharing system to open the file. All systems that subsequently open the file will use the shared cache specified by the first system.
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