The gzsetparams() function shall set the compression level and compression strategy on the compressed file stream referenced by file. The compressed file stream shall have been opened in a write mode. The level and strategy are as defined in deflateInit2.. If there is any data pending writing, it shall be flushed before the parameters are updated.
On error, gzsetparams() shall return one of the following error indications:
Invalid parameter, or file not open for writing.
An internal inconsistency was detected while flushing the previous buffer.