Input Processing Output
1 When the attention interruption is received, issue DIAGNOSE B code X'7B' subfunction X'04'. "- J\. 2 If VM/370 has a request, build INVALID REQUEST CODE IN V SVC 126 parameter list, issue
v
VM REQUEST SVC 126; otherwise, go back
into wait state. 3
Upon return from SVC 126, issue DIAGNOSE code X'7B', subfunction code X'OB' (only
if MSC accepted).
Return to Step 1.
Notes Module Label Ref Notes Module Label Ref
1 This loop will run in the VS DMKMSS MAINLOOP machine as long as MSS support
is in effect. The DIAGNOSE X'7B' instruction points to a
buffer in DMKMSS into which VM/370 places an MSSCOM, or
zeros.
2 Look at MSSCOM to determine L2
volume serial, 3330V device
address, and type of request
(mount or demount). If the RFOO149 request is inval id, issue a
message. If there are no out· standing requests, go into a wait RFOO122 state.
3
The SVC 126 routines issue
orders to the MSC. If the MSC DIAG rejects the order, it sends a unit
check as ending status. SVC then sets a non·zero return code MSSCHECK in register 15. niaaram 12-2. DMKMSS Processing
226 IBM VM/370 Service Routines Program Logic

Program Organization
This section describes the program organization of the DMKMSS module. DMKMSS The MSS communicator program. Point tMKMSS Usage BO-R9: Work registers R10: Workarea base
R11: Program base B12: Work register
B13: legister savearea base R14-R15: Work registers
Chapter 12. MSS Communicator 227