HELP: ZSTD data compression technique TYPE: OBJECT SYNTAX: ZSTD(LEVEL=num/FAST/LEV1/LEV2/LEV3/LEV4/LEV5/LEV6/LEV7/LEV8/LEV9/LEV10/LEV11/LEV12/LEV13/LEV14/LEV15/LEV16/LEV17/LEV18/LEV19/BEST/AUTO)
The ZSTD compression conforms to the ZSTD-compression tool on UNIX-systems. The compression level can be set to values from 0 to 9 (0=fastest, 9=best).
The default level is 6 when no level is specified.
Decompression of concatenated ZSTD files is also possible. All concatenated files are decompressed into one file. It is also possible to decompress one specific member of this concatenation by specifying the member index of the file to be decompressed:
filename/:memberindex
If ZSTD compression is used with write.record(), the file attributes cannot be stored in the ZSTD file. The record attributes can be added in front of the record (PRNCTR=RETAIN). By default, a 4 byte length field in little endian is written in front of the data. Such an ZSTD file can be used on record-oriented platforms to recreate the original datasets as PS-VB. You may want to use a ZIP archive or ARMOR encoding to store the file attributes (DCB) to recreate the correct record format and length.
NUMBER: LEVEL=num/FAST/LEV1/LEV2/LEV3/LEV4/LEV5/LEV6/LEV7/LEV8/LEV9/LEV10/LEV11/LEV12/LEV13/LEV14/LEV15/LEV16/LEV17/LEV18/LEV19/BEST/AUTO - Compression level [AUTO==9]
FAST - Fastest compression (ZSTD_minCLevel())
LEV1 - Compression level 1
LEV2 - Compression level 2
LEV3 - Compression level 3
LEV4 - Compression level 4
LEV5 - Compression level 5
LEV6 - Compression level 6
LEV7 - Compression level 7
LEV8 - Compression level 8
LEV9 - Compression level 9
LEV10 - Compression level 10
LEV11 - Compression level 11
LEV12 - Compression level 12
LEV13 - Compression level 13
LEV14 - Compression level 14
LEV15 - Compression level 15
LEV16 - Compression level 16
LEV17 - Compression level 17
LEV18 - Compression level 18
LEV19 - Compression level 19
BEST - Best compression (ZSTD_maxCLevel())
AUTO - Automatic compression (level 9)