+$! Check To See If We Have A ZLIB Option.
+$!
+$ ZLIB = P8
+$ IF (ZLIB .NES. "")
+$ THEN
+$!
+$! Check for expected ZLIB files.
+$!
+$ err = 0
+$ file1 = f$parse( "zlib.h", ZLIB, , , "SYNTAX_ONLY")
+$ if (f$search( file1) .eqs. "")
+$ then
+$ WRITE SYS$OUTPUT ""
+$ WRITE SYS$OUTPUT "The Option ", ZLIB, " Is Invalid."
+$ WRITE SYS$OUTPUT " Can't find header: ''file1'"
+$ err = 1
+$ endif
+$ file1 = f$parse( "A.;", ZLIB)- "A.;"
+$!
+$ file2 = f$parse( ZLIB, "libz.olb", , , "SYNTAX_ONLY")
+$ if (f$search( file2) .eqs. "")
+$ then
+$ if (err .eq. 0)
+$ then
+$ WRITE SYS$OUTPUT ""
+$ WRITE SYS$OUTPUT "The Option ", ZLIB, " Is Invalid."
+$ endif
+$ WRITE SYS$OUTPUT " Can't find library: ''file2'"
+$ WRITE SYS$OUTPUT ""
+$ err = err+ 2
+$ endif
+$ if (err .eq. 1)
+$ then
+$ WRITE SYS$OUTPUT ""
+$ endif
+$!
+$ if (err .ne. 0)
+$ then
+$ EXIT
+$ endif
+$!
+$ CCDEFS = """ZLIB=1"", "+ CCDEFS
+$ CC_INCLUDES = CC_INCLUDES+ ", "+ file1
+$ ZLIB_LIB = ", ''file2' /library"
+$!
+$! Print info
+$!
+$ WRITE SYS$OUTPUT "ZLIB library spec: ", file2
+$!
+$! End The ZLIB Check.
+$!
+$ ENDIF
+$!
+$! Check To See If The User Entered A Valid Parameter.