Should I block it?
No, this file is 100% safe to run.
 
     
    
        jaclib.dll
| MD5:    | ac07acbb4fb1edb677523c6467c31a66 | 
| SHA1:    | ae6c77f6b93067ee76d658b261724f58d1d2a491 | 
Overview
jaclib.dll is loaded as dynamic link library that runs in the context of a process. This particular version is usually found on Windows 7 Home Premium (6.1.7601.65536).
Details
| File name: | jaclib.dll | 
| Typical file path: | C:\.jagex_cache_32\runescape\jaclib.dll | 
| Size: | 129 KB (132,096 bytes) | 
| Build date: | 1/24/2014 8:35 AM | 
| Digital DNA | 
| File packed: | No | 
| .NET CLR: | No | 
More details
Distribution by Windows OS
| OS version | distribution | 
| Windows 7 Home Premium | 
100.00% | 
 | 
Distribution by PC manufacturer
| PC Manufacturer | distribution | 
| Hewlett-Packard | 
100.00% | 
 |