clSetKernelArg and variable lifetime

How does OpenCL specification say about the length of lifetime of a variable which passed for clSetKernelArg?

For example,

    int x;
    clSetKernelArg(0, sizeof(x), &x);

The variable x is dead when kernel execution, is this fine?

I know it works on the current major implementations (e.g. CUDA, ROCm). But we need to think about the portability based on the specification because we’re using “open standard”.