Operating a JIT compiler in a randomly allocated memory for secure execution of unsigned code

A method, system and program for operating a Just in Time (JIT) compiler to compile and execute unsigned code in a randomly allocated memory area. Application code is received (210) and unsigned portions of the code are identified (212). Identification of the code may use a flag within the code. An area of memory is then allocated to the operation of a JIT compiler (224) and the code is compiled and executed (220) as if it were signed code. The unsigned executable portion of the code is processed by an application having a specific entitlement which may be granted on a certificate and provisioning profile and/or enforced using a public/private key infrastructure. The memory region allocated to the JIT executable code may be restricted to a single memory area and may not be reused during the process lifetime of the application. A memory page containing the selected random area may not be shared.