Use this system macro to release an input/output control block (IOCB)
address.
Format
- label
- A symbolic name can be assigned to the macro statement.
- BLOCK=Rx
- This register contains the address of the I/O block that is to be
released.
- WKREG=Ry
- The register specified will be used as a work register.
- TEST
- This parameter is used for testing and problem determination
purposes.
- NO
- It is intended that this is used for production systems. The code
to get IOBs expands in-line.
- YES
- This is used in a test environment to generate code to go to a central
routine (see the CL$RIOBC entry point in the CLHV segment of the CCSTOR CSECT)
when releasing an IOB. It is useful in monitoring IOB list
accesses. It only takes effect if the global variable SBCTEST is set on
(BX'1') within this routine.
The default is NO.
Entry Requirements
The program that invokes this macro must be running with a storage
protection key of zero. It must also be operating in 31-bit
mode.
Return Conditions
- Control is returned to the next sequential instruction (NSI).
- The condition code is not set on return.
- The block released is no longer available for program use.
Programming Considerations
- This macro can be run on any I-stream.
- Register R0 is used internally by the macro and should not be used to
specify the address of the block or be used as a work register.
- If the TEST parameter is used in an online system, severe system
degradation results due to I/O constraints.
- The TEST parameter must only be used in test environments.
Examples
None.