Guardian Procedure Calls Reference Manual

number (whole word boundary); thus, 3 rounds up to 4, and so forth. ODDUNSTR prevents this rounding,
so that reading, writing, or positioning occurs at the exact RBA specified. (See Considerations (page 235).)
Specifies data compression for key-sequenced files. (For additional information, see the Enscribe
Programmer's Guide.)
<12>
Specifies the file structure:<13:15>
Unstructured (default)0
Relative1
Entry-sequenced2
Key-sequenced3
recordlen
input
INT:value
for structured files, is the maximum length of the logical record in bytes. In H06.28/J06.17
RVUs with specific SPRs and later RVUs, the maximum record length for format 2 key-sequenced
files is 27,648; for format 2 entry-sequenced files, the maximum record length is 4048; for
format 2 relative files, the maximum record length is 4044. (For a list of the required
H06.28/J06.17 SPRs, see SPR Requirements for Increased Enscribe Limits for the
H06.28/J06.17 Release (page 31).) For format 1 entry-sequenced and relative files, the
maximum record length is 4072. If omitted, 80 is used. For queue files, this parameter must
include 8 bytes for a timestamp. This parameter is ignored for unstructured files.
The formulas for computing the maximum record length (MRL) based on data-blocklen are:
MRL equalsFor this type of file
data-blocklen - 24Relative and entry-sequenced
files
data-blocklen - 34Key-sequenced files
data-blocklen
input
INT:value
for structured files, is the length in bytes of each block of records in the file. In H06.28/J06.17
RVUs with specific SPRs and later RVUs, the maximum block length for format 2 key-sequenced
files is 32,768; for format 1 or 2 entry-sequenced and relative files, the maximum block length
is 4096. (For a list of the required H06.28/J06.17 SPRs, see SPR Requirements for Increased
Enscribe Limits for the H06.28/J06.17 Release (page 31).) For earlier RVUs, the maximum
block length is 4096, regardless of the file organization or format.
For a format 2 key-sequenced file, the value of data-blocklen must be at least recordlen
+ 34; for format 1 or 2 entry-sequenced and relative files, the value of data-blocklen must
be at least recordlen + 24.
Regardless of the specified record length and data-block size, the maximum number of records
that can be stored in a format 2 data block is 16383; the maximum number of records that
can be stored in a format 1 data block is 511. For unstructured files on 512-byte sector disks,
a block length 4096 is used unconditionally, and the user has no control over the buffer size
used internally (as distinguished from 514-byte sector disks).
Data-block sizes are rounded up to power-of-two multiples of the sector size: 512, 1024, 2048,
4096, or 32,768. For example, if a 3K byte block were specified, the system would use 4096.
230 Guardian Procedure Calls (C)