p = gcp returns a parallel.Pool object representing the current parallel pool. The current pool is where parallel language features execute, such as parfor, spmd, distributed, Composite, parfeval and parfevalOnAll.

If no parallel pool exists, gcp starts a new parallel pool and returns a pool object for that, unless automatic pool starts are disabled in your parallel preferences. If no parallel pool exists and automatic pool starts are disabled, gcp returns an empty pool object.

p = gcp('nocreate') returns the current pool if one exists. If no pool exists, the 'nocreate' option causes gcp not to create a pool, regardless of your parallel preferences settings.