The IOCC_UNIT_CONTROL CommandCode consists of all the CommandModifiers responsible for controlling the ownership of a unit. The following table describes the CommandModifiers.

┌────────────────────────┬────────────────────────────────────┐
│CommandModifier         │Description                         │
├────────────────────────┼────────────────────────────────────┤
│IOCM_ALLOCATE_UNIT      │Assigns ownership of the specified  │
│                        │unit to the caller.  A unit must be │
│                        │allocated prior to accepting any    │
│                        │other direct call commands. Once    │
│                        │allocated, a unit cannot be assigned│
│                        │to another owner until that unit is │
│                        │deallocated.  It is the             │
│                        │responsibility of the owner to      │
│                        │coordinate sharing of a unit.       │
├────────────────────────┼────────────────────────────────────┤
│IOCM_DEALLOCATE_UNIT    │Removes the caller's ownership of   │
│                        │the specified unit.  Once           │
│                        │deallocated, a unit can be assigned │
│                        │to another owner.                   │
├────────────────────────┼────────────────────────────────────┤
│IOCM_CHANGE_UNITINFO    │Modifies the specified unit's       │
│                        │UNITINFO portion of the DEVICETABLE │
│                        │structure with the information      │
│                        │passed by the caller.               │
└────────────────────────┴────────────────────────────────────┘

Support:

Mandatory
Called By:
OS2DASD.DMD, other device manager, or filter device driver
Context of Call:
TASK

Format of IORB

• IORB Type
  -
  IORB_UNIT_CONTROL
  
  IORBH Fields
  -
  CommandCode
  
  --
  IOCC_CONFIGURATION
  -
  CommandModifiers
  --
  IOCM_ALLOCATE_UNIT
  --
  IOCM_DEALLOCATE_UNIT
  --
  IOCM_CHANGE_UNITINFO
  -
  Valid RequestControl Flags
  --
  IORB_ASYNC_POST

  IORB_UNIT_CONTROL Description

  This section defines the IORB_UNIT_CONTROL control block. (See the table below.)

  ┌─────────────────┬─────────────────┬─────────┬─────────────────┐│Field Name       │C Type           │Length   │Description      │
  ├─────────────────┼─────────────────┼─────────┼─────────────────┤
  │iorbh            │IORBH            │DB(68)   │IORB header      │
  ├─────────────────┼─────────────────┼─────────┼─────────────────┤
  │Flags            │USHORT           │DW       │Flags            │
  ├─────────────────┼─────────────────┼─────────┼─────────────────┤
  │pUnitInfo        │PUNITINFO        │DD       │Pointer to       │
  │                 │                 │         │UnitInfo         │
  ├─────────────────┼─────────────────┼─────────┼─────────────────┤
  │UnitInfoLen      │USHORT           │DW       │Length of        │
  │                 │                 │         │UnitInfo         │
  └─────────────────┴─────────────────┴─────────┴─────────────────┘
  

  On entry to the driver:

  iorbh
  See IORB General Format.

  Flags
  contains a 0.

  pUnitInfo
  contains a far pointer to a buffer containing modified unit characteristics, in the format defined by the UNITINFO structure. The adapter device driver uses this information to update the unit's UNITINFO structure in the DEVICETABLE. This field is valid only for the IOCM_CHANGE_UNITINFO CommandModifier.

  Note: A device driver can access the UNITINFO structure provided by the IOCM_CHANGE_UNITINFO IORB at any time. The caller, therefore, must not invalidate or release the passed UNITINFO structure on successful completion of this IORB request.

  UnitInfoLen
  contains the length, in bytes, of the UNITINFO buffer (pUnitInfo) passed to the driver. This field is valid only for the IOCM_CHANGE_UNITINFO CommandModifier.

  On exit, the driver sets the Status and ErrorCode fields of the IORBH to reflect the results of the IOCC_UNIT_CONTROL request.

  Return Codes

  Following is a list of the IOCC_UNIT_CONTROL error codes:

  IOERR_CMD_SYNTAX
  IOERR_CMD_SW_RESOURCE
  IOERR_UNIT_ALLOCATED
  IOERR_UNIT_NOT_ALLOCATED

  For a detailed description of all the return codes, see Error Handling.

  ---

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