Sharing printers between systems

If you plan to share the use of a printer other than the master, IMS allows an online IMS system and another subsystem (possibly another IMS system) to alternate their use of the printer.

The IMS support is for VTAM® 3270 printers and, in the SNA environment, for LU–1 and LU–4 printers. The /OPNDST NODE Q command simulates a logon to IMS for the requested printer. The printer is automatically acquired when the owning subsystem frees the printer. You can queue output at any time independently of printer availability.

The system definition requirements are for the OPTIONS keyword of the TERMINAL macro. Specify:
OPNDST
so that the /OPNDST command is valid for this terminal
SHARE
so that the VTAM macro SIMLOGON can be issued by IMS in order to acquire the printer when data is queued for output
RELRQ
so that IMS releases the terminal to other VTAM subsystems upon their request

Specify RELRQ on the ETO logon descriptors to have the same features available for ETO terminals.

Each output message that is queued to a shared printer attempts a session.

As an alternative to immediate logon simulation and repeated failures while trying to acquire messages, you can use the Shared Printer exit routine (DFSSIML0). This exit routine monitors terminal (or transaction) status, and takes one of three actions:
  • Ignores the request
  • Simulates the /OPNDST command
  • Queues a transaction for an automated operator program

The Shared Printer exit routine is not called if the printer is connected. You specify the SIMEXIT keyword in the IMS startup parameters to call the Shared Printer exit routine. DFSSIML0 must be placed in an authorized library in the JOBLIB, STEPLIB, or LINKLIST library concatenated in front of the IMS.SDFSRESL.

Recommendation: Do not share the secondary master terminal.