With the introduction of support for the HMC integrated 3270 console (HMCS) we also get a new state for HMCS and MCS consoles called STANDBY. Let's take a look at what this new state means.
STANDBY is a new state for a console, so now we have three states of interest (ACTIVE, STANDBY, INACTIVE).
Standby State is a new state for HMCS and MCS
- Must be in full capability (FC) mode
- SMCS, EMCS, subsystem consoles, the System Console, printer consoles or consoles in status display (SD) or message stream (MS) mode are NOT supported.
- Defined on a per-console basis
Consoles in Standby state are
- part of the 99 active consoles per system limit (when in distributed mode)
- part of the 99 defined consoles per Sysplex limit (when in shared mode).
System resources are pre-allocated for consoles in Standby, so activation of console is faster as control blocks for the console are pre-allocated.
- New keyword SUPSBY=Y must be enabled for console
The is a new keyword SUPSBY for an MCS and HMCS console:
- Indicates if console supports Standby
- SUPSBY is NOT supported on Printer, Subsystem, SMCS or EMCS consoles
- Always “Y” for HMCS consoles and cannot be changed
If you display a console you'll see the new keyword and value in the display:
SC74F400 TYPE=MCS STATUS=ACT-SC74
ATTRIBUTES ON SC74
AUTH=(MASTER) CMDSYS=* NBUF=0 SUPSBY=N
DEV=F400 LOGON=OPTIONAL USERID=N/A
MFORM=(T,S) AREA=(Z) PFKTAB=*DEFAULT
USE=FC DEL=RD RTME=1/4 RNUM=20 SEG=20 CON=N
MONITOR=(NONE) INTIDS=Y UNKNIDS=Y
You can specify the SUPSBY as part of the MCS console definition in the CONSOLxx member.
- Default is SUPSBY(N)
- For example
You can also change it dynamically via VARY CN(consolename),SUPSBY=Y|N
- If console already in Standby, SUPSBY=N is rejected
- You can only change for MCS consoles in USE(FC) mode
A display for console SC74F400 will show the value for SUPSBY.
VARY CN(xx) command used to put console into Standby
- Can be used if device is currently “offline” or “active”
- VARY CN(XX),STANDBY
I/O errors cause console to go into Standby instead of “offline”
- SUPSBY=Y must be enabled
This is a handy feature for MCS consoles.
For example, say you use an OSA-ICC MCS console for operations during the day and you close the session and head home.
Now you get call a during the night for a problem and you want use the OSA-ICCC MCS console.
Today when you initially connect to the console all you get is the connection screen to the OSA-ICC session.
To activate the console you have to issue the MVS command to do so.
Which means logging into the system and using SDSF to issue the command or asking an operator to do so.
However, if you define the console as SUPSBY=Y, then all you need to do to activate the console is hit an attention getting key!
So for example: (assume OSA-ICC operator console session)
- Changed SC74F400 to SUPSBY=Y
- End console session by closing emulator; console goes to standby state.
- Now, I log back onto the console
- The console state is changed from STANDBY to ACTIVE
Here's a summary of the states and transitions between states:
That's rather handy! For more nifty features available with z/OS Version 2 Release 1, see the IBM Redbooks Publication z/OS Version 2 Release 1 Technical Updates, SG24-8140.