DBCCMD expects standard OS linkage conventions. The TSO CALL command invokes the called program using these conventions. In particular, Register 1 must point to a parameter list, and other registers to different areas, as follows:
| Register | Description |
|---|---|
| R1 | Pointer to parmlist. |
| R13 | Pointer to a 72-byte save area (will be used). |
| R14 | Return address to calling program. |
| R15 | entry address of DBCCMD. |
Construct the parmlist and argument as follows:
| parmlist: | 1 full word containing address of argument. (Bit 0 should be set to b’1’ to indicate the last parameter.) |
| argument: | +0: 2-byte length of following parmstring. +2: command parmstring, as described earlier. |