Use this system macro to return a storage block to the TPF system.
The storage block can be any logical block or a system work block
(SWB).
Format
- label
- A symbolic name can be assigned to the macro statement.
- BLOCK=Rn
- This parameter is used to return the block address to the TPF
system. The register specified must contain the 31-bit storage block
address to be returned to the TPF system. The block address returned
will be correct for the address space currently being used: an EVM
address if ADSPACE=EVM, an SVM address if ADSPACE=SVM.
- ADSPACE
- This parameter gives the address space where the calling code is
operating.
- EVM
- The code issuing this macro is operating in the EVM on behalf of an
ECB.
- SVM
- The code issuing this macro is operating in the SVM and may or may not be
operating on behalf of an ECB.
- ECB
- This parameter specifies whether the block is currently connected to the
ECB virtual memory (EVM).
- YES
- When ECB=YES, the frame containing the block must currently be connected
to an ECB's virtual memory. The ECB must be on the I-stream where
the $RELBC was issued.
- NO
- The block address being returned must be an SVM address. The frame
containing the block cannot be part any ECB's virtual memory.
- EXIT=YES
- EXIT=YES is a special interface for EXITC processing. During EXITC
processing a check must be made for VEQR mode. If VEQR is On, all
blocks must be released. If VEQR is Off, only common blocks must be
released. This parameter is only valid for the EXITC service
routine.
- SAVREG
- The specified volatile registers will be saved by the macro in
the stack area or in the registers specified by the WKREG parameter. Up
to 3 registers can be specified. Those registers are R0, R1, R2.
If this keyword is omitted, none of the 3 registers will be saved. You
should not save a volatile register if you expect it to contain an output
parameter. The register will be overwritten with its original contents,
since the reload is the last thing performed by the macro.
- WKREG
- The specified symbolic register names are free to be used by the macro to
save the volatile registers coded on the SAVREG parameter.
Up to 3 registers can be specified, but the standard linkage registers R13
through R2 cannot be used here. This parameter is used in conjunction
with the SAVREG parameter to generate efficient code and enhance the
performance of the macro. The number of registers specified by WKREG
should be less than or equal to the number of registers specified by
SAVREG. If this parameter is omitted or not used to its maximum
capacity, code optimization is sacrificed.
Entry Requirements
- The program invoking this macro must be running in a privileged mode of
operation and with a storage protection key of zero. The program must
also be operating in 31-bit mode. The address space of the code issuing
this macro must be correctly specified via the ADSPACE parameter.
- R13 is assumed to contain the stack pointer.
Return Conditions
- Control is returned to the NSI.
- The contents of the register specified in the BLOCK parameter are
unpredictable.
- The condition code is not saved.
Programming Considerations
System error dumps can occur when servicing a $RELBC request.
See Messages (System Error and Offline) for more
information about system errors.
Examples
None.