Use this system macro to perform a software dismount of a symbolic device
address (SDA) that is associated with an input/output (I/O)
device. Once this macro is processed for an SDA, the SDA is unavailable
for any additional I/O until another MSDAC macro is issued for the
SDA.
See MSDAC-Mount a Symbolic Device Address (SDA) for more information about the MSDAC macro.
Format
- label
- A symbolic name can be assigned to the macro statement.
- SDA
- The SDA, which can be either of the following:
- label1
- A halfword field that contains an SDA.
- (reg)
- A register that contains an SDA in bytes 2-3 and zeros in bytes
0-1.
Entry Requirements
- The TPF system must be disabled for interrupts.
- The TPF system must be running with PSW key 0.
Return Conditions
- Control is returned to the next sequential instruction (NSI).
- One of the following return codes is returned in register 15 (R15):
- Return Code
- Meaning
- 0
- The dismount is successful.
- 4
- The dismount is not successful.
- The contents of all other registers are preserved across this macro
call.
Programming Considerations
- This macro can only be run on an I-stream having affinity with the
specified SDA.
- This macro can be used only to dismount SDAs associated with I/O
devices.
- This macro is for use in the control program (CP) only.
Examples
None.