All the file attributes described below can be assigned via the ADD-FILE-LINK command (see manuals [9] "BS2000 Commands").
If no specifications are made and the file attribute cannot be ascertained by reference to the catalog entry or tape labels, the default value defined by PERCON takes effect (see also section “Priority of assignments” on chapter "I/O assignment ".
ACCESS-METHOD
Access method for the file. PERCON can use the access methods SAM, ISAM, UPAM and BTAM.
Default value:
Input files are read using the access method specified in the catalog entry.
The following applies to output files:
File copying in disk files: | ACCESS-METHOD=*ISAM |
File copying in tape files: | ACCESS-METHOD=*SAM |
Tape editing: | ACCESS-METHOD=*SAM |
Format-edited files are always SAM files.
If the output file is to be an ISAM file, the records to be output must be sorted in ascending order of key. This may be the record counter, which can be inserted in the output record by means of a SET-RECORD-MAPPING statement.
BLOCK-CONTROL-INFO
This new file attribute defines the block structure. It is the result of eliminating the PAM key (see "PAM key elimination ") and is relevant for the access methods SAM, ISAM and PAM.
A distinction is made between the following attributes:
PAMKEY: | 16 bytes of management information (PAM key) are assigned to each 2-Kbyte block; these 16 bytes do not form part of the 2-Kbyte block. |
WITHIN-DATA: | Each logical block contains 12 bytes of system information. |
NO: | The file contains no system information. |
The file attribute BLOCK-CONTROL-INFO is part of the catalog entry. New files are given this attribute on the basis of a default specification which depends on the volume, the system parameters BLKCTRL and ISBLKCTRL and the file access method.
BUFFER-LENGTH
Block size of the file. Files consist of standard blocks (BUFFER-LENGTH=*STD). Nonstandard blocks (BUFFER-LENGTH=*NSTD) can also be specified, but only for tape files.
The block size influences the maximum record length. If the record to be output is too long, the record will be truncated.
For format-edited files, the entry BUFFER-LENGTH=*STD(SIZE=n) always applies. The value of SIZE depends on the pubset format:SIZE=1 with 2K-formatted pubsets,SIZE=2 with 4K-formatted pubsets.
For newly created output files, this value applies by default.
The primary size of a file should always be at least twice the BUFFER-LENGTH value, whereas the secondary allocation value should be at least the BUFFER-LENGTH value.
RECORD-FORMAT
Record format of the files. PERCON supports the record formats FIXED, VARIABLE and UNDEFINED.
Default value: RECORD-FORMAT=*VARIABLE
Format-edited files always use the variable record format.
RECORD-SIZE
Record length. With RECORD-FORMAT=*FIXED, the length of the records to be output is specified; with RECORD-FORMAT=*VARIABLE, the maximum length of the records is specified. If an output record is longer than specified in the RECORD-SIZE operand, the record is truncated. If RECORD-FORMAT=*FIXED is specified and the output record is shorter than specified in the RECORD-SIZE operand, the record is padded with space characters (X’40’).
If no record length or record length 0 is specified or if the specified length exceeds the maximum value determined for BUFFER-LENGTH (see the table below), this maximum value is assumed for the length of the output record.
ACCESS-METHOD | BLOCK-CONTROL- | RECORD- | Maximum value |
SAM | PAMKEY | VARIABLE | BUFFER-LENGTH - 4 |
WITHIN-DATA-BLOCK | VARIABLE | BUFFER-LENGTH -16 | |
NO | VARIABLE | BUFFER-LENGTH - 4 | |
ISAM | PAMKEY | VARIABLE | BUFFER-LENGTH |
WITHIN-DATA-BLOCK | VARIABLE | BUFFER-LENGTH | |
PAM 1) | PAMKEY | BUFFER-LENGTH | |
WITHIN-DATA-BLOCK | BUFFER-LENGTH - 12 | ||
NO | BUFFER-LENGTH | ||
BTAM | VARIABLE | BUFFER-LENGTH |
1)The RECORD-SIZE specification is not used to determine the maximum value.
2)Applies to tape files only.
3)Applies only when the current input file uses ACCESS-METHOD=*UPAM and BLOCK-
CONTROL-INFO=*PAMKEY and when no output file specifies BLOCK-CONTROL-INFO=*WITHIN-DATA-BLOCK or *NO.
KEY-POSITION
Position of the ISAM key in the output record (relevant for ISAM files only).
Default values:
RECORD-FORMAT=*FIXED: KEY-POSITION=1
RECORD-FORMAT=*VARIABLE: KEY-POSITION=5
KEY-LENGTH
Length of the ISAM key in the record (relevant for ISAM files only).
Default value: KEY-LENGTH=8
OPEN-MODE
Open mode of the file. The *EXTEND value can be used to add the records to be output to an existing SAM or BTAM file. In the case of SAM files, the records read in can be written back to the input file if both the input file and the output file were opened with OPEN-MODE=*UPDATE. In this case the current output record has the same length as the current input record. If necessary, it is truncated or padded with blanks until the lengths are equal.With ISAM files, the output records can be inserted at the appropriate place by virtue of their key fields, provided OPEN-MODE=*OUTIN (for new files) or OPEN-MODE=*INOUT (for existing files) was specified.
Default values:
For input: |
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For output: | PAM files: |
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