Defining command prefix strings (CPFs)

Each subsystem instance of IBM MQ can have a command prefix string to identify that subsystem.

Adopt a system-wide convention for the CPFs for all subsystems to avoid conflicts. Adhere to the following guidelines:

• Define a CPF as string of up to eight characters.
• Do not use a CPF that is already in use by any other subsystem, and avoid using the JES backspace character defined on the system as the first character of our string.
• Define the CPF using characters from the set of valid characters listed in Table 2.
• Do not use a CPF that is an abbreviation for an already defined process or that might be confused with command syntax. For example, a CPF such as 'D' conflicts with z/OS commands such as DISPLAY. To avoid this happening, use one of the special characters (shown in Table 2 ) as the first or only character in your CPF string.
• Do not define a CPF that is either a subset or a superset of an existing CPF. For an example, see Table 1.

  Subsystem name	CPF defined	Commands routed to
  MQA	!A	MQA
  MQB	!B	MQB
  MQC1	!C1	MQC1
  MQC2	!C2	MQC2
  MQB1	!B1	MQB

  Commands intended for subsystem MQB1 (using CPF !B1) are routed to subsystem MQB because the CPF for this subsystem is !B, a subset of !B1. For example, if you entered the command:

  !B1  START  QMGR
  

  subsystem MQB receives the command:

  1 START QMGR
  

  (which, in this case, it cannot deal with).

  We can see which prefixes exist by issuing the z/OS command DISPLAY OPDATA.

  If we are running in a sysplex, z/OS diagnoses any conflicts of this type at the time of CPF registration (see CPFs in a sysplex environment for information about CPF registration).

Table 2 shows the characters that we can use when defining your CPF strings:

Character set	Contents
Alphabetic	Uppercase A through Z, lowercase a through z
Numeric	0 through 9
National (see note)	@ $ # (Characters that can be represented as hexadecimal values)
Special	. ࿄ ( ) * & + - = ¢ < | ! ; % _ ? : >

Note:

The system recognizes the following hexadecimal representations of the national characters: @ as X'7C', $ as X'5B', and # as X'7B'. In countries other than the U.S., the U.S. national characters represented on terminal keyboards might generate a different hexadecimal representation and cause an error. For example, in some countries the $ character might generate an X'4A'.

The semicolon (;) is valid as a CPF but on most systems, this character is the command delimiter.

Parent topic: Define the IBM MQ subsystem to z/OS