This is a set of tiny programs (old, old, old) which invoke some IBM 
service for maintaining SYS1.BRODCAST .  I haven't tested them in a
while, but I suspect they still work.  They should be rewritten to use
the now-documented service routines, but I never got around to it and 
I don't need or use these programs at Stanford.  USE AT YOUR OWN RISK.
When I have time to locate the source, I'll replace bc-load.netdata
with some other file containing the source.  In the meantime, all I
have handy is the load modules.  They are all TSO commands:

ADDBC - adds the execution userid to the SYS1.BRODCAST directory.  
ADDBCX xxx - adds userid xxx to the directory.
DELBC xxx - removes userid xxx from the directory, AND DELETES ALL
          QUEUED BRODCAST MESSAGES.
LSTB - read SYS1.BRODCAST directly (no IBM service routine used, so
          if the format changes, this program may break.)
  Operands for LSTB:
     xxx     - displays (does NOT remove) queued messages for xxx.
     = LIST  - displays a list of the userids in the directory.
     = INDEX - displays a list of userids with queued messages.
     = USAGE - displays number of queued messages by userid.  *high overhead*

Obviously you'll probably want to restrict access to all of these
programs except ADDBC.