MQCFST - PCF string parameter

The MQCFST structure can also be used for user-defined message data. In this case the message descriptor Format field is MQFMT_PCF (see Message descriptor for a PCF command ). Also in this case, not all the fields in the structure are meaningful. The supplied initial values can be used for most fields, but the application must set the StrucLength, StringLength, and String fields to the values appropriate to the data.

The structure ends with a variable-length character string; see the String field section for further details.

See Usage notes for further information about how to use the structure.

StrucLength (MQLONG)

Structure length.

This is the length in bytes of the MQCFST structure, including the string at the end of the structure (the String field). The length must be a multiple of four, and must be sufficient to contain the string; any bytes between the end of the string and the length defined by the StrucLength field are not significant.

The following constant gives the length of the fixed part of the structure, that is the length excluding the String field:

MQCFST_STRUC_LENGTH_FIXED

Length of fixed part of command format string-parameter structure.

Parameter (MQLONG)

Parameter identifier.

This identifies the parameter with a value that is contained in the structure. The values that can occur in this field depend on the value of the Command field in the MQCFH structure; see MQCFH - PCF header for details.

The parameter is from the following groups of parameters:

• MQCA_*
• MQCACF_*
• MQCAMO_*
• MQCACH_*

CodedCharSetId (MQLONG)

Coded character set identifier.

This specifies the coded character set identifier of the data in the String field. The following special value can be used:

MQCCSI_DEFAULT

Default character set identifier.

The string data is in the character set defined by the CodedCharSetId field in the MQ header structure that precedes the MQCFH structure, or by the CodedCharSetId field in the MQMD if the MQCFH structure is at the start of the message.

StringLength (MQLONG)

Length of string.

This is the length in bytes of the data in the String field; it must be zero or greater. This length does not need to be a multiple of four.

String (MQCHAR x StringLength)

String value.

This is the value of the parameter identified by the Parameter field:

• In MQFMT_ADMIN command messages, if the specified string is shorter than the standard length of the parameter, the omitted characters are assumed to be blanks. If the specified string is longer than the standard length, it is an error.
• In MQFMT_ADMIN response messages, string parameters might be returned padded with blanks to the standard length of the parameter.
• In MQFMT_EVENT messages, trailing blanks might be omitted from string parameters (that is, the string can be shorter than the standard length of the parameter).

The value of StringLength depends on whether, when the specified string is shorter than the standard length, padding blanks have been added to the string. If so, the value of StringLength is the sum of the actual length of the string plus the padded blanks.

The string can contain any characters that are in the character set defined by CodedCharSetId, and that are valid for the parameter identified by Parameter.

Note: When the queue manager reads an MQCFST structure in an MQFMT_ADMIN message from the command input queue, the queue manager processes the string as though it had been specified on an MQI call. This processing means that within the string, the first null and the characters following it (up to the end of the string) are treated as blanks.

In responses and all other cases, a null character in the string is treated as normal data, and does not act as a delimiter for the string. This treatment means that when a receiving application reads a MQFMT_PCF, MQFMT_EVENT, or MQFMT_ADMIN message, the receiving application receives all the data specified by the sending application.

The way that this field is declared depends on the programming language:

• For the C programming language, the field is declared as an array with one element. Storage for the structure must be allocated dynamically, and pointers used to address the fields within it.
• For the COBOL, PL/I, and System/390 assembler programming languages, the field is omitted from the structure declaration. When an instance of the structure is declared, the user must include MQCFST in a larger structure, and declare an additional field or additional fields following MQCFST, to represent the String field as required.