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.