#### ZSTD

#### Synopsis

    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)

#### Description

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.

#### Arguments

- `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)`