We present a generic approach for the analysis of concurrent 
programs with (unbounded) dynamic creation of threads and recursive 
procedure calls.
We define a model for such programs based on a set of term rewrite rules
where terms represent control configurations.
The reachability problem for this model is undecidable.
Therefore, we propose a method for analyzing such models
based on computing abstractions of their sets of computation paths.
Our approach allows to compute such abstractions
as least solutions of a system of (path language) constraints.
More precisely, given a program and two regular sets
of configurations (process terms) T and T', we provide
(1) a construction of a system of constraints which characterizes
precisely the set of computation paths leading from T to T',
and (2) a generic framework, based on abstract interpretation,
allowing to solve this system in various abstract domains leading
to abstract analysis with different precision and cost.