The link register (LR) contains the return address (a halfword address) for a RET instruction. A CALL instruction saves the last return address into the stack and updates LR with the return address. A RET instruction uses the current value of LR as the target address and restores the last return address into LR from the stack. The LR is shown in Figure 8-40 and described in Table 8-322.
Figure 8-40 Link Register (LR) | LEGEND: R = Readable by the MVC instruction; W = Writeable by the MVC instruction; -n = value after reset |
Table 8-322 Link Register (LR) Field Descriptions| Bit | Field | Value | Description |
|---|
| 31 | Reserved | 0 | Reserved. The reserved bit location is always read as 0. A value written to this field has no effect. |
| 30-0 | Return Address | 0-7FFF FFFFh | Contains the return address (a halfword address) for a RET instruction. |