sp_cop errors out with message "Not enough space calling shmat to attach to shared memory segm (4297266)

When trying to start sp_cop after a previous shutdown, the following errors are observed in the event log:

EVENT_LOG:

02/16/11 01:41 Notice: Result (12) Not enough space calling shmat to attach to shared memory segment (3002) [sp_ordr(shs)/4107]

02/16/11 01:41 Error: que_init: Cannot attach to shared memory [sp_ordr(que)/4107]

02/16/11 01:41 Notice: Error opening output queue que_SHMERR: Shared memory error que_open(-,FHexpQueue+X,0x70406754+PR+o.ssordprd+sp_ordr+o.ssordprd) [sp_ordr(rim)/4107]

02/16/11 01:41 Notice: data route to 70406754.1.bf failed err=100 [sp_ordr/4107]

02/16/11 01:41 Error: 11004 - sp_ordr failure writing to queue(s) [sp_ordr/4107]

02/16/11 01:41 Notice: Exit sp_ordr to retry rim-write. [sp_ordr/4107]

02/16/11 01:41 Process exited sp_ordr  (for o.ssordprd) [pid = 4107] - exit(1)

02/16/11 01:41 Process launched: sp_ordr (for o.ssordprd) [pid = 9695]

02/16/11 01:41 Notice: Oracle env - ssordprd:/apps/opt/oracle/product/10.2.0 [sp_ordr(pdb)/9695]

Also:

11/24/08 13:26 Notice: Result (12) Not enough space calling shmat to attach to shared memory segment (3002) [sp_cop(shs)/27943]
11/24/08 13:26 Error: que_init: Cannot attach to shared memory [sp_cop(que)/27943]
11/24/08 13:26 Error: queue initialization failed - exiting [sp_cop/27943]

Here the messages when sp_cop is failing to start:
$./sp_cop -u2200 &
queue initialization failed - exiting
que_SHMERR: Shared memory error